Can someone please provide some insight into the listening difference between the Vandersteen 1C and the 2CE? I am familar with the new signature 2CE's but they're out of my price range, so am thinking of these as preowned purchases.

No comparison. The IC throws a smaller soundstage, is less transparent and has nowhere near the bass of the 2CE.

Perhaps, but given a good amp (they are a bit amp finicky) the sound can be quite close. We found you also need to sit closer to the 1's than the 2's. The 1's are an extremely good buy if that's all you can afford. I can't remember any other thousand dollar speaker that gives you so much. Just remember the amp can make a big difference.
Own IC's. In my ears, they throw a "broad" soundstage which is very pleasant to listen to. Chashas1 is correct - Nearfield behaves much better. I've seen updates where the socks are removed, and a smaller ribbon tweeter is mounted on the top as well as repleacing the speakers with kevlar woven B&W parts. Offers you definition in the high/mid ranges. Do not exepect lots of base out of these. They need to be driven somewhat hard to sound good in my experience. To me, the best of its advantage is the "Broad" soundstage.
We have both these speakers. The 1C's were purchased used here and fill a living room with great sound with inexpensive NAD equipment. The 2CE signatures are in the den and sound fuller, warmer and yes, have more bass......more "there" there as they used to say in the magazines. HOwever, having said that, we listen to the 1c's for music more these days because of their location while the 2's in a larger space do double duty with the TV/blu ray. I don't think you can go wrong with either one of these all around good performers.
There are many threads on Audiogon devoted to Vandersteen speakers. Do a search, and you'll be able to read many insightful comments on the Vandersteen sound.

For me, in my room, with my system (click on my "system") the 1C's are pretty perfect. Plenty of soundstage (width and depth), a wonderful combination of dynamics and truth of timbre, excellent extension at both extremes, and an incredible "musicality" that I really enjoy. The speakers beautifully complement my tube amplifier and both my analog and digital front ends, and I can listen for hours and hours without any "listening fatigue."

My 1C's are about 6 feet apart, my chair is about 7 feet away, and the speakers are tilted as per Richard's explicit instructions. This is a great arrangement in my room, and the 1C's do a great job. I keep thinking of one day upgrading to the 2Ce Sig. II's, but for now, I love my 1C's. Happy Listening !!
If you've got the room, the 2's are a big step up from the 1's, but if your room is too small you'll be better off with the ones. IMHO, the 2's are the best deal in the Vandy lineup, and perhaps in all of audio.
There is no fair comparison, as the 1C is only half of the 2CE. The 1C is the 8" woofer and the tweeter, while the 2 models all have the woofer and tweeter as well as the 10" accoustic coupler and a 5" midrange. Having heard them all, and having owned Models 2C, 2CI, 2CE, 3, 3A, and 4, I can't say enough good things about the 2CE.
But back to your original question, the comparison. The midrange, or lack of one, makes a big difference. Most people say that 80% of the listening we do is in the midrannge. Thus having a speaker in the system that is devoted to the midrange adds definition and nuance to the overall sound, and it also lets the other speakers concentrate on a narrower range of the audio spectrum so they can reproduce more precisely. Having the 10" accoustic coupler fills out the bass and gives the speakers body and bottom. The 1C is a great 8" 2 way speaker, but it can't compare to the 2s. It's like minor league versus major leage baseball. They're both playing the same sport, but one gives you so much more than the other. Save your pennies and buy Model 2s. I listened to the new 2CE Sig IIs, and they are wonderful, but my old Model 2s were great, and my 2CIs had so much soul. You can find used 2CEs here on Audiogon for $500-$650, so if it's achoice between buying new ICs or any used Model 2 buy the 2s. You'l be sorry if you don't.
Good Luck, MJWPicMan.
I have heard both go for the 2ce,much nicer speaker.If you find them lacking in a certain area, just change the amp,make's the biggest difference.