Let me get this straight, you posted asking people to share their top speeds, then you don't believe the results when they tell you. Why did you ask in the first place.....
We all know Tom and he is not the type to just throw stuff out there, this likely really happened to him, (most everyone carrys GPS's these days by the way).
A normal TI with a standard sail I'm pretty sure can easily run .6 of the wind speed. so in a 40mph wind .6 is 24mph. Of course as speed goes up the horsepower required to drive the displacement hull goes up exponentially. Here is a website where you can calculate the speeds yourself ( http://www.psychosnail.com/boatspeedcalculator.aspx
Running through the formula with an 18 ft boat at 400 lbs the max speed is 12.1 knots (according to the formula)
In the example I entered it takes around .6 horsepower to propel the boat 6mph, but it take 47 hp to propel the boat 10 mph, (sail force needs to be thought of as to horsepower of course).
With the formula set to a 7 mph desired speed it takes 1.5 hp to propel the boat. I have a gas 2hp motor on my TI and the max speed in smooth water is around 7mph (I don't think I'm getting the full 2 hp into the water), but this kind of confirms the formula (at least in the limited range (below max), What it does show is the amount of horsepower required to propel a floating log past the hull speed.
So obviously the TI hull has some planing going on because I have had mine up to 18-19 mph on many occasion in under 22mph winds. That by the way was measured with GPS and not just for a few seconds. On one occasion I was sailing from Ft Desoto Island to Egmont key in open water (about 9 miles), about 4 miles was a downwind reach with the wind at around 20-22mph the wind angle was coming from around 220-230, I had all 265 sq ft of sail out and maintained 18 to 19 mph the whole distance (measured with GPS), with me and my wife aboard, as well as coolers, scuba gear and two tanks lashed to the AKA's.
Another occasion was down in key west the winds were a steady 20-23mph, Just me and wife (no coolers, scuba gear, and scuba tanks this time so we were not at max weight). The wind was again coming from around 220 deg, we maintained around 18 mph with the main and spinnaker deployed (no jib this time, as it was interfering with and collapsing the spin so I furled it). We were chasing down and following one of the big Sabago sailing cats (the Marquesa is 70 ft with one of the largest sails in south florida (according to their website), just to say hi, my wife works down there and knows alot of the crews. The run was 2-3 miles. The spin also creates a lot of lift so it helps lift the front of the hull so we plane a little better. I removed the hydrofoils from this new boat ( my 3rd TI, don't need them anymore since I added the two ft bow sprit. Next time we do a run like that I will do some video.
The formula fails at around 12mph so this is kind of telling us that the TI hull is not the same as pulling a floating log through the water (ie.. putting an outboard on a log LOL), there is some planing going on. The reason I added hydrofoils to my older TI's was specifically to get the bow out of the water at faster speeds (just so it could plane some). Part of the trick is to try to keep the weight aft (fat guy (me) in the back), and hike out so the AMA's don't bury (the nylon sheer bolts break at higher speeds (I have sheared at least 4 while underway).
With just the mainsail, trying to keep more weight aft, and hiking out (with the hydrofoils engaged on a 20 plus mph downwind reach I used to be able to do around 14 mph (measured on GPS), turn off the foils and I would slow down to around 12mph (more drag from the bow (boat goes back to a log LOL)). The foils do rob some speed, as do the mirage drives, If someone were to tape up all the mirage and scupper openings, you can likely go faster, as long as you can keep the bow and AMA's out of the water, and the rudder as neutral as possible.
I find that on a broad reach (90 deg to the wind) the tipping force is greater, and it is really difficult to keep the AMA's from burying (which slows the boat down), so a 90 deg reach is not the fastest on these boats.
Actually with my boat I get the best upwind performance with the jib. In higher winds you have full sails out and keep the boat pointed as tight as possible into the wind, be careful though, if you relax and turn away from the wind a little with that much sail out, you definately will go over, or at the very least totally bury one AMA (which slows you right down). The trick is hiking to keep the AMA out of the water. In 15 mph winds I can easily get up to 7-8 mph pointing about 20 deg off the wind with the jib, maybe 5 mph without the jib, but it's hard to get closer than 30 degrees to the wind and still maintain speed without the jib, of course with the TI you can sail straight into the wind if your willing to peddle a little, but it's not fast.
As soon as I get closer to 90 deg off the wind I have to furl the sails a little or your just dragging the AMA through the water. It seems on the TI in winds greater than 15mph you actually go faster on a reach with the sail furled a little ( a turn or two).
I suggest you have someone with real sailing experience go out with you, they can give you a lot of valuable pointers on how to read the sails, which sails to fly and when, reading winds, weight distribution, and drag. Just little things like rudders create great drag if not used correctly.
My advise if you want to get the most out of your TI, don't get too comfortable in that seat (good weight distribution helps just as it does in a Laser or Sunfish). The sail design on the AI/TI's is a really good modern boomless sail design, and can be sailed easily by someone with no sailing experience at all, but to get the most out of it requires a little sailing experience and knowledge.
Sailing Cats like the H16, etc is a different knowledgebase I can understand how frustrated a cat sailer would be in a TI or AI, but a laser or sunfish sailer would have a good time.
Hope this helps you, and you should apologize to Tom.