Cyclocross - An exception in sizing?

I used to ride a 62cm (by my measurement) Schwinn Continental. I've ridden it on rides as much as 65 miles and this last month was riding it 100 miles a week. It seemed to work for what I was doing and seemed to be a good size. (Although I did raise the stem to just past the maximum line.)
Then I was hit by a car and the frame was bent.
I went to a bike store and rode a 56cm Fuji cyclocross bike. (It was the only 'cross bike they had.) I rode it and it felt great, but it is so different than the Schwinn that I cannot tell if it fits different. The people at the store said it looked like a good fit when I was riding it. The top tube length is good and the seat could be adjusted for my legs.
I am 6'0 with a 35" inseam. From what I have read, I should be on a 58 or 59cm.
I am very wary of buying this bike, even though it feels comfortable to ride, because conventional wisdom tells me it is too small.
Is it possible that a 56cm is a good fit. Does anyone else my size ride a bike that small?

Without knowing anything else, I would guess one size higher would be better. I bet there is a lot of seatpost showing when you ride that 56, which means there is that much more drop from saddle to bars. If you were a pro cyclist, that's probably what you'd want. For the rest of us mere mortals, and especially for cross, it's better to have a more neutral stance.

Do they have a Fuji road bike in 58? I'd try that out for comparison.

cross bikes seem huge to me...i ride a size down from what i normally ride...mine is a 54

What is your height and inseam?

try the competitive cyclist fit calculator

http://www.competitivecyclist.com/za/CCY?PAGE=FIT_CALCULATOR_INTRO
(i recommend the eddy fit)

then read this

http://cyclocrossworld.com/Tech.cfm?Action=Edit&MenuKey=3&theKey=43&ShowDisabled=0

if you are of average build, guessing off your height i'd put you on a bike that has a tt of about 57 and 100-110mm stem.

Thanks for the advice. The competitive cyclist fit calculator was especially helpful.

I found a Fuji cyclocross bike with all Ultegra components on sale for $900. Seems like a great deal, but it is a 56cm and I can't find anyway to justify buying a bike that is too small.

you should never compromise on fit, unless its to strip all the parts and move to a frame that works well with your body.

And I don't think it is a good enough deal to do that. It can get very tempting though.

Another awesome deal will come by soon.