@123GO: I'd be happy to tell you a little about the differences, although sounds like you've already got your EPQ, right?
Anyway, here's some pics of my Colnagos which I posted in the Pictures of Colnagos thread some time ago:
My EPQ with Boras and Campy 80th (Since this pic was taken I've removed 7mm of spacers and steertube).
My EPQ in it's "classic" configuration...
My C50 (ST02)...
And all three: C50, C59, EPQ
The C59 and and EPQ are identical geometries and setups. Both 61 Traditional. This summer I made an effort to see if I could discern what differences there were between the EPQ and C59. I rode them both quite a lot, same saddles, same wheels, same tires etc. As far as removing all the different variables that can arise when trying to compare bikes I think I pretty much had it covered. The only difference is the bars and stem although they are both very close to each other in shape and are set up to as close to the same as possible.
Here's my thoughts:
1) I do not like one more than the other. They are basically just different looks. The C59 is matte and aggressive looking. It's got the SRM. I like it on group rides when we might duke it out in some sprints here and there and I can look back later on Training Peaks to see how I did powerwise etc. That's not to say it's any faster than the EPQ, but it does look more aggressive I guess. It gets a lot of "badass beautiful" comments.
2) The EPQ is a beautiful timeless design. The top tube and downtube are from the EPS, although the top tube has been reworked a bit to fit into the squarish seat cluster lug of the C59. The top tube and downtube are essentially round in cross section as well, which I wanted on this paint scheme. Everything else is shared with the C59. The EPQ can look equally as stunning with classic box section rims and 32 spokes as it does with carbon Boras. The C59 on the other hand, being matte black, really shines when paired with some deeper profile carbon wheels. I ran it with some Neutrons for a while and the whole look was pretty blah, black bike... so what. I think I prefer the EPQ with the classic wheels but I rode it most of this summer with the Boras, so I could compare with the C59. Which brings me to...
Love 'em both and can't really tell the difference. If there is a difference, it would be because of a different setup or using different wheels etc. I think magazine reviews attempting to talk about differences between frames are a joke quite frankly. They are comparing different setups, different sizes, different everything really. And then they have to come up with some drivel to meet a deadline before print. Sometimes, I wouldn't be surprised if they get no more than a few hours on the bike. To appreciate a bike, any bike, you have to ride it enough to get to know it and adjust accordingly. And that just doesn't happen in a couple of test rides. I'm sure you will be happy with your EPQ providing it fits you. I have to say that I probably enjoy riding my EPQ a bit more just because of what it represents to me in the whole grand scheme of what cycling is to me. Now that I have had a summer riding it with the Boras I think the majority of riding I do with it will be with the classic wheels. I love the ride of them. Silent smoothness. They're strong and predictable, and I don't feel like they're hindering me from getting to any destination I might care to go to. I could ride any of these bikes all day every day.
Compared to the C50:
We're really splitting hairs now. The C50 is a wonderful bicycle. I've had two. I got my first one after selling my C40 (first colnago), then I "crashed" that into the top of my garage one day and ended up getting the ST02 you see above as a replacement. I guess maybe the C59 is a bit "snappier" as you seem to think, but I'm not about to say the difference is that staggering.
Bottom line: You've already bought it. You'll probably like it. Where did you get it? New or used? Show us a pic. Start a build thread.