If you love it, then there's no reason I can think of not to get it. Half the battle of finding a used Colnago is getting a color scheme you like, the other half being finding the size you need. I presume both of those criteria are met here.
The Extreme Power and EPS are two high end Colnagos I have not owned. I never really cared for the Bayleaf chainstays although some people love them. They are definitely unique to both the Extreme Power and EPS models. The Extreme Power has the external headset whereas with the EPS they went to the internal headset and pressed in cups. The Extreme C actually had a weight limit on it, so it was not a frame that I would have ever coveted. The other frames you mentioned become sort of very similar in my opinion and colour scheme and size becomes the biggest determining factor. So, if you like the look of the EP more than any of the C59 or C60 schemes, then I say go for it. I have to admit that aside from not really liking the bayleaf chainstays, when the EPS came out they went down a road of very swirly curly paint schemes that I never got used to. It wasn't until they brought out the PR99 and Saronni Red and Zabel blue (I forget the numbers) that I thought... yes, now THOSE I like. But paint and graphics are all very subjective, if you like it that's what counts.
To clear up a couple of things that @ColnagoEPQ mentioned... the EPQ came about really at the beginning of the C59 era, not the end. I was quite involved with it at that time. Like I mentioned, even though I had just ordered my MTBK C59 (Fall of 2010), the latest PR99 of the EPS was gnawing at me big time. I loved that colour way. So I just went ahead and ordered one, even though I had a C59 on order at the same time. A couple of months passed before they got back to me saying that they couldn't do it in my size because they had run out of stays for it. We mulled it over for a while, and I remember discussing in detail as we looked over an EPS frame and wondered what could be done. Keep in mind this was well before they had even come up with the name "EPQ". I had all but given up when they came back with a picture of a "prototype" (really just a mish mash of EPS tubes that they still had along with the new C59 lugs) sitting on what I like to think was Ernesto's desk. I still have the emails somewhere I'm sure, I hope. It was really the perfect solution. It had the top tube and downtube of the EPS (roundish cross sections), and everything else, including the lugs, was from the new C59 (I hadn't even received my C59 frameset at this time). This meant that the derailleur cables would be internally routed, entering through the C59 lugs), while the rear brake cable would still be the traditional external with cable stops on the EPS top tube. To make the EPS top tube fit into the rear seat cluster lug (which was squarish versus round), they just reworked the top tube to fit the C59 lug and voila... The EPQ (still not named), was born. I said "Perfect, I want it"... then the wait began. In the meantime, I received my C59, built it up, and it became quite popular, etc. Finally, the following summer, I received my "EPS", but the graphics were all changed, much to my dismay. That was not what I had ordered. So, I didn't take it, and that was the end of that, or so I thought... until Alex Colnago came visiting the shop one day and heard the story and took it upon himself to restart my quest for the new frame if I still wanted one. I said "Sure, if you can do it the way I want, then I'll take it". I think and appreciate that a certain friend in the UK may have had some influence on Alex as well in my quest for this frame. Fast forward to just before Christmas of 2011, and guess what shows up... my "EPQ" frameset as you see it in my build thread. No mention of "EPQ" anywhere on it, as that was one of the changes they made which I said "WHAT?" about. So, that is a very special frameset to me, very clean, no marketing crap, just a few paneled Colnago logos and decals and the "proper" chevrons on the forks and stays. It is my modern "classic" so to speak. Love that bike.
But back to your decision... Will it be comfortable enough? Yes, I think so. Will it be stiff enough? Yes, I think so. Will you regret buying it, and want something else down the road? Hmmm... you may want and get something else down the road, but I doubt you'll regret getting the EP... especially if you're liking the way it looks as much as you seem to be right now. And if everything does indeed go to discs, etc., well, at least you'll still have one bike that looks like a proper road bike
What color scheme is it that has caught your eye, and what size? Got a pic?
Oh, on tire clearance... you'll probably be limited to 24mm clinchers (25mm tubulars) on newer rims to be safe. You can fit larger with a C60, but even still 25mm is about the biggest I'd want to go and still have a good margin of clearance all round. Personally, I have no interest in using a road bike with larger than 25mm tires on the road. But if people can convince you to use 30mm tires on the road, then they're often seen rubbing their hands together, saying "Ha, we got 'em... now he HAS to switch to discs... Mwwaaaaahhahah".
Just get it, post it up... It's Enresto's birthday week after all.