Seems like an amp list might be heavily biased to simple measurements, and it’s tough to meaningfully measure either speaker or amp, never mind their interaction. Most Thiel models drop below 3 ohms over part of the audioband but what can you say about how phase angle confounds that? Might be even worse with amp measurements. And to predict the interaction from measurements? Good luck!
I drove my CS1.6s with an Ayre AX-7e, 60 W into 8 ohms, doubling into 4. The 1.6 impedance drops to about 3 ohms over part of the audio band. AX-7 has 66 1 dB steps on the volume control. I usually listened at about 30, maybe low 40s if I had the house to myself and wanted to rock out (my room is 18 x 19 with a vaulted ceiling and two large openings on the rear wall). Much louder than that and it became painfully loud. I found out later, when I switched to the low efficiency Vandy 2, that my combo of amp and source would result in clipping starting at about 45 on the volume control. That little amp had plenty of balls to drive the “low” impedance Thiels.
Yes, some Thiels are tough loads. The CS5 comes to mind, dropping to about 2 ohms in the low bass and even lower where musical content peters out. So, extra care is probably a good idea for some models. But most any amp that is comfortable at 4 ohms can probably adequately drive most Thiels.
The extra headroom from more power is certainly audible and desirable but less so, IMO, than the SQ from a superb amp regardless of its measurements. As it says it Thiel’s manuals, most users will be happier with a great 100 W amp than a mediocre 200 W amp. If a list must be done, I suggest maybe categories of amps: clearly underpowered, probably adequate depending on user/room, and fully adequate. I would not dismiss out-of-hand a “mere” 100 W amp. Just look at the many reports of good results with tubes!
