Thanks all, really appreciate the wide range of responses - plenty to look at there and lots to research.

I'll definitely look into the freewheeler - that seems like the cheapest and quickest solution to many of our problems.

We'll definitely test-drive the K2, since there's a dealer just 30 miles from us, and we can borrow one for a weekend, apparently. But I think there's a lot of other avenues to investigate, so thanks again to everyone who responded so far.