I've done several Raylar kits and they work great. I've dyno'd them and they make the power claimed. One customer has a couple of hundred hours on his package and it gets run very hard. No trouble at all.
What it will do to the boat value? That's a tough question. It won't raise it to equal a 525 Merc engine. It will probably increase the value some, but it could also narrow the resale market. As with anything in boating, you don't do it for an investment.