I'm not really referencing anything in particular. I have done a bunch of searches on this forum and asking questions to get people's experience.
Also check out:http://w1dm.com/projects/HOTLINE/Hotline.html
for a bunch of old articles on boat repair and restoration specific to hobies.
I've completely sanded down one hull at this point. My only advice is use 60-80 grit paper, don't even bother or think about anything higher. I started with a 100 because I was being cautious but that was really a waste of time. I've probably put in about 8-10 hours of sanding on the one hull alone. Very boring and tedious but it's part of the process.
If you are only thinking about brightening up your hulls and they are white I would strongly urge you to avoid doing gelcoat and look at the many other methods first and using soda blasting for the anti-skid deck.
If you are thinking of changing the color then yes you have a harder decision to make. I can tell you that sanding down the anti-skid is a major PITA but it is necessary if you want to truly change the color of the hull. At least half my time was spent sanding it off. I'll post some pics later so you can take a look.
I chose gelcoat because I wanted to change the color of the hull and I wanted to be able to simply sand and buff any scratches out. Gelcoat is more durable and has better maintenance to it. I expect to wet sand and buff it once a year to restore it to basically new at the start of the season. With paint, scratch repair is a little bit more troublesome and you can easily show the white gelcoat underneath.
I know lots and lots of people will try to tell you to just paint it and there are lots of good reasons. It's definitely much less work, cheaper and there are plenty of really good durable marine paints out there.
I'm a bit of perfectionist and it would drive me insane to think there was a better process out there. Gelcoat is certainly not cheap or easy to work with. I just ordered 2 gals of colored gelcoat, 1 gal of Duratec, and the requisite hardner. I also bought the gelcoat spray gun (which I could sell to you for cheap when I am done) and some other random supplies. Otherwise I have an air compressor and sanding tools in my shop. Total cost was right around $500! And that was with a 20% off coupon that fiberglast.com had during cyber week. Luckily I was literally about to order when I got the coupon. Saved me some good money. That's about a 1/3 of the cost of what I paid for my boat. You also probably have to be more aware of temperatures with gelcoat and I'm having to install a heater in my garage, although that's something I've been wanting to do for a while so the wife isn't that surprised and it isn't that expensive. Northerntool has some good garage heaters for around $100.
I've done a few restoration projects where I barely paid anything for the item itself but spent lots more money just getting the item to look and perform the best. To me it's worth it and I enjoy putting the time in and seeing the finished result. If you don't have the patience, room, or time necessary then I don't recommend doing gelcoat. My hulls will be hanging in my garage/man shack for a good two months by the time I am done and that is just for the gelcoat. It will probably take me about another month to slowly put the boat back together. I hope to be ready for the water by March. Of course I don't have kids and my wife is out of town every week from Monday-Friday. I've also closed my office for the entire week of Christmas so I'll be doing a lot of the work that week as we are staying in town.
As an example of a restoration project I once paid $35 for a 1928 17" Delta Drill Press that had really been put through the ringer at a metal machine shop. It was in sad shape. I completely stripped it apart and rebuilt it, painted it, buffed it and now it is literally in showroom shape and is a gorgeous piece of antique machinery that performs flawlessly. I probably spent around $300-$400 on bringing it back to life but it was worth it. It's the first thing anyone notices when they walk into my garage, apart from the 1970 fully restored Vespa that I have in there that is painted the colors of the Italian/Mexican flag.
My gelcoat arrives tomorrow and I'll probably start spraying next week. I have to drag some new power lines to the garage to handle the 240V heater and the increased amps I'll be pulling with the compressor, vent fan, spot lights, etc. Working with my electrician buddy this week to make that happen by the weekend.
I'll post some pics later this week. Let me know if you have any other questions.