Thiel 3.5 upgrade to 3.6 or 2.4 worthwhile?

Hi Everybody,
With some wonderful help from forum members, I have my recently aquired Thiel 3.5s sounding really good. I'm using an Oppo 83SE player with a Threshold FET9 preamp and a Hafler 9500 amp with Kimber PBJ interconects and Symphony cables. I am loving the sound with no disatisfaction, but am already looking for a step up in the sense of being closer to a live performance.
So, what I'm wondering is would a move to either the 3.6s or 2.4s be a substantial improvement or an incremental one? The 3.5s are old, but in great shape and the equalizer is working well, so I am not too concerned about reliability. The issue for me is the sound. I know Thiel speakers have improved since the 3.5s, but since the company's design goals have remained constant I'm just not sure the change in performance would be that great.
I would really appreciate hearing from Thiel afficiandos who have heard all three models about their impressinons of the differences in realisim of the sound of these models.
Thanks in Advance,
IMHO, the newer Thiels are smoother higher up, but the older 3.5's have better bass (as long as it's not too loud), are more coherent, and (though high a quality amp with preferably at least 200 Watts into 4 Ohms is needed), even with the eq, easier for an amplifier to drive. I prefer the 3.5's, and think when new and especially used, are amongst the greatest audio values of all time, others will prefer the newer models.
The 3.5 is a high value speaker system. I never owned the 3.5s but listened to it at a dealer's showroom. At the time, it was a great speaker.

I auditioned the 3.6s at the same dealer before I bought it and thought they sounded better than the 3.5s. The 3.6 was more transparent, dynamic, and quicker transient attack. However, in the wrong position, its bass could be overwhelming. It could be too generous and made the images bloated.

I borrowed the 2.4s to audition at home and thought they sounded more neutral. It didn't have the 3.6s deep bass, but its soundstaging was bigger. The images were a bit smaller than the 3.6s. In a smaller room, I would prefer the 2.4s. If you have to position the 3.6s very close to the back wall, the bass would be hard to tame unless you have lots of acoustic treatment.

I won't say it would be a quantum leap in sound quality upgrading to the 3.6s or 2.4s. I personally think the less components in the audio chain the better. So I don't prefer the extra equalizer in the system.

Regardless, you should try to audition either the 3.6s or 2.4s before making the decision. There could be a very nice synergy between your 3.5s and the rest of the components.
I would put the money in a better amp if it were me. Also I find PBJ to be a little sticky at times; sorry the Devil made me do it.
I used to owned Thiel 3.6 for a long period of time. It was perpectly powered by a pair of McCormark DNA-1 mono block delux edition rev.A. The pream was CJ PV15. Sound was remarkable transparent, coherent and very quick transition attack. My cousin had a pair of 2.4 so he and I decide to gave the Thiels a head to head comparision. Both have a similarity in sound characteristic while the 3.6 has bigger soundstage and more pronounce bass, the 2.4 is better in voices and images, a tad more refine than the 3.6 (may be due to the newer midrage and coaxial driver). We also agreed that the 2.4 was easier on placement. At end of the day, we were very please with the result and could easily leave with either speaker.
I'm with the try out a new amplifier camp, Perhaps a different speaker cable first as that may suffice until you can save if need be? Just from my experience i can tell you the AMP makes a huge difference in what your listening experience will be. I run the 2.4's with a BAT VK-600 and they sing beautifully together and provide more than enough bass in a 13x11x11 room but its so much more refined a presentation that the massive power supply can give. I'd look into dual mono design or monoblock amps with at least 300w per channel. In fact with a fuller and richer sounding speaker cable its almost too bass heavy. I've read those Kimber's sound good with the Thiel though.

Happy hunting
Thanks for the input so far,
As an update, I have replaced the Hafler with a B&K Ref 2220 amp I recently got from a fellow Agoner and feel it is a noticable improvement in that the sound is a little sweeter and the bass noticably more robust, but still well defined. The change wasn't major but it was affordable and worthwhile.
I'm wondering now if upgrading the interconnects and speaker cables have the potential to give me as much improvement as the amp upgrade since the ones I have in the system now are considered to be very good for the money. I have seen in the past that interconnects and speaker cables can make a noticable difference but suspect that I will be getting into an area of substantially diminishing returns if I go this route. Any thoughts would be appreciated.