I have a Dahon Piccolo (about $250) and an el-cheapo Z-bike picked up a few years ago for $89 from Heartland. Happy with the aluminum and mostly-stainless Dahon, and the z-bike is good for what it's worth, all steel basic Chinese off-the-shelf low-end components. It's been wiped annually with anti-corrosion spray and if it rusts too much I'll replace it.

I don't think it pays to spend too much on a boat bike -- there's a middle ground and that Downtube Nova looks like it's in there somewhere. You might need to upgrade the seat or extend certain components if you're tall, but bike parts are pretty easy to customize or replace at low cost.

It's a PITA to take even the folders ashore, but once there we will leave them locked up ashore overnight if we're staying in a harbor for the next day. It really increases our range to explore or provision, and bike riding is a good way to get the flavor of a place. Some places better than others for riding, and it's nice to have them available. Provincetown was great for bike riding, as are many other stops.

The shot below overlooking Buzzards Bay was taken a few years ago after about a 10 mile bike ride along Horeseneck Beach in Westport MA. We discovered a great restaurant out in the middle of nowhere that would have been inaccessible without bikes. They had a peach-raspberry pie that was heaven.