If you are planning to "invest" as you say, does your budget extend to a tandem mirage drive kayak (either new or second hand)?
1. First reason I ask is that my experience of trying to get either of my SWMBOs (one is ~21 years old, the other 9) to paddle a paddleyak for any distance was that it was like pushing you know what up a hill. Paddling a single is bad enough, paddling a double with 2 occupants would IMO be a nightmare. Pedalling a 2-up Hobie Mirage Drive Tandem is not particularly tough once you have "match fitness" in your legs (I have just been doing it this weekend - 2 blokes, one drive, slightly slower but similar range to a single). You are into kayaking to enjoy it, as is your crew, and a mirage drive boat will probably prove a much more enjoyable experience all round.
2. Second reason is that (as a result of 1) you will probably get far and away fewer sea miles under your keel in a tandem paddleyak than you could with a mirage drive yak - so a paddleyak might be cheaper up front, but in terms of cost per mile and enjoyment per dollar the mirage drive boat will probably win hands down.
3. Have you tried/thought about kayak sailing yet? This is one of the aspects of the Hobie boats that I like the best. my friend and I sailed for miles 2 up on a Mirage tandem perfectly well and in total comfort and safety at the weekend.
4. Have you thought about resale value? (Hobie Mirage drive boats are well sought after on the second hand market and so hold their values pretty well so, if you can afford the cost of entry, it is not likely to prove a total dog of an investment: you will go further, faster, have more fun, possibly enjoy sailing too and when you decide to move on you should recoup a decent part of your initial investment.)
5. You mention safety. On a mirage tandem you have 4 possible means of getting back to shore: two drives; one drive; sail; paddle - or a combination of these. Mirage drive boats are relatively unaffected by headwinds but have you ever tried paddling a loaded kayak into a strong headwind? (IMO not fun!)
Have a think... perhaps try an Oasis if you can before you make your mind up!