I own the latest 2CE Sig III and auditioned the Treo CT at the time I was deciding, and since. Also the Quatro CT, and have spent time in front of the 7 with the top Vandy monoblocks (AMAZING system). All are listed as Editors’ Choices in their price brackets by Absolute Sound in their Recommended Components guide, iirc.
There is a consistency of sound, the "Vandersteen Sound", among them. I would say it comes down to budget. IMHO, the 2CE is a best buy and punches way above its weight. But, if spending $10k (vs $3500) is in the budget, the Treo CT is superb and is much better looking. I may soon get the Treos. BUT—again IMO—I think the Quatro CT is in the sweet spot of performance vs value in its price-range and in the Vandersteen lineup, when compared to the top of the line 7 (really great) or even the Kento. There is really no wrong answer. I would REALLY love a pair of Quatro CTs.
It is quite common to see Vandy owners move up from the 2 or 3 to the Treo, and then to the Quatro or Kento as/if funds allow. So, "worth the money?". Only you can decide that. There is the law of diminishing returns in high-end audio, and to some of my friends spending even $3500 on speakers is insane, but I would gladly spend the $$ on the Treo CT or Quatro CT.
There is a member here who has the Treo CT and the 7 with monoblocks (which I have heard). Maybe a 10X difference in price and I asked him specifically if he felt like the Treos come up short compared to his 7's. "No way," he said. He said there is a consistency in the sound, and that he loves the Treos but that the 7 is just more of a great thing.
CAVEAT: The Treo and Quatro are superbly-resolving speakers and will highlight any deficiencies elsewhere in your system. It is important that the components upstream are up to the task, including cabling. I have an Odyssey Audio Khartago+++ amp, and though it’s not super expensive I like it and it’s a Jon Valin best-buy, I think it would be adequate or fine with the Treos. A more expensive amp *might* even be better (I would like the Ayre VX-5/Twenty maybe, or mono blocks, for the Treo). Richard Vandersteen recommends "zero negative feedback" amps like Ayre, and so do many dealers. A good Vandersteen dealer will tell you about good pairings (Optimal Enchantment in Santa Monica, or John Rutan at Audio Connection in NJ are two...where are you?).
I am not a card-carrying fanboy, blindly loyal, but I have found Vandys to be speakers I can live with for a long time, and I don’t have the money to scratch every itch and jump from brand to brand. Vandys are extremely musical, for lack of a better term, and let you forget about them and just enjoy the music. For me, that is the goal. GOOD LUCK!
The 2CE and Treo are on this AbSound list of 50 Greatest Bargains in High-End Audio 50 Greatest High-End Bargains List