Oh, hiya! Just spotted this in the old Google Analytics vanity search!
Yes, I'm riding a Superfly for my Wales Coast to Coast ride this summer. I'm currently training on the top AL version, doing the actual ride on the Carbon XX jobbie.
I gave my initial thoughts here so won't go into too much detail: http://www.garyrides.co.uk/2011/12/trek-superfly-100-al-pro-first-thoughts/
In short I'm a big fan, I genuinely just enjoy riding it on all terrain and could easily be a candidate for my 'one' bike. I find it lively, not overly 29er ish in feel when you consider the negatives (thanks to the G2 geometry I guess) but very much a 29er in feel on the usual positives - read: still steamrolls everything but fun and whippetty too. Very slack (68 deg) for a 100mm 29er FS but handling and wheelbase is very much on par with a 68 degree 26er FS. So even in twisty singletrack I've found it to be very responsive.
Accurate is a word I'd use, rider inputs translate into the trail as you intend (might sound weird but not sure how else to say it). I'd always felt Treks were very good but maybe not as fun as they could be. I find the Superfly very fun and cheeky even. I ran a dropper post for a bit and descending with the saddle right down it felt more like a fun trail bike than a race bike. Obviously I'm assuming the lighter carbon ones will feel naturally more racy too (this one is 28lb w/pedals).
Sure I've been loaned it and have to say nice things, but would I buy one tomorrow? Absolutely.
Oh and I'm a bordering on Hobbit-like 5'8" and riding a 17.5", so I don't know how the sizing is effecting the handling and whether that reflects in flatfishy's experience? But it definitely rides well in smaller sizes at least.