My view is that NA1 prices won't increase much more - the market for "proper" premium classics has reached some silly heights and we're seeing a number of collectors 'rationalising' their collections. If that market dips, then it'll push down on everything below.
So on that basis I'd be sticking with a car I know well rather than an unknown machine with an unknown collection of issues to fix (potentially). I'd also stick with what I enjoy driving the best - NA1s are never going to be cars to make a proper profit out of, so you may as well enjoy the one you've got.
I could be wrong, of course, but that's my 2p...
"No man with a good car needs to be justified"
Blue '08 FD2 CTR - big, ITR-sized shoes to fill...
Yellow '96 NSX 3.0 - oh was it worth the wait!
Black '99 ITR - well, I had to have another one, the first was so much fun. Miss this one even more than #1...
Blue '03 S2000 - SOLD, flawed but fun
Blue '04 Focus TDCi Sport - SOLD, very good fun for a diesel!
Black '00 ITR - SOLD, still missed
Red '98 Civic VTi - SOLD, probably still bombproof