This answer may be a little lame - but here it goes anyhow. Note that I have been away for decades and my personal experience listening to music through a robust system ended with the 3.5 and the following 2.2. Now I have PowerPoints and 2.2s and have heard a few systems when visiting folks. So my experience is rather dated. But it was full-emersion / intense.
So my reason for loving the 3.5 is personal. I was intimately involved in its development, parts sourcing, voicing, manufacture and tweaking. Those 3D baffles were all hand-carved by . . . moi and an assistant, in an amazing hand of man effective method . . . and then tooled on a vintage inverted router (souped up with an 8" diameter forming tool that I designed. You get the picture, full frontal engagement. The fiber (silk, paper) upper drivers do not have the resolution of metal, but they are more forgiving. The woofer was our first polypropylene and we custom designed the cone profile for significant breakup improvement. The caps in the 3.5 were Solen when Solen was using their own best-in-world French film. The micro bypasses were 1% styrene x tin foil. Lots of tweaking and voicing and audiophile sensibilities. Later products lost that last level of detail due to cost / value engineering. There just wasn't enough improvement for the considerable extra cost. Also the newer metal drivers changed the cost / performance equation again and caps suffered - inserting a little vague jangle, in my opinion. I have always locked on bass authenticity from my musician and recording days of youth. The 3.5 sealed bass has a rightness from the very bottom that just doesn't quite bloom with reflex bass. OK, the reflex bass hits all the adjectives better - tight, punchy, etc. and plays more than twice as loud. But the sealed bass of the 3.5 and 5, digging lower than the recording, somehow lights my fire more naturally.
To your question. New Thiel models and generations always mitigated the problems of the previous generation and improved everything they addressed, within the limits of balanced performance. I think a newer, bigger model would almost always please more people more often. Try to audition some.
The gist of my quest is to resurrect some of the old models which can be had at bargain prices and apply lessons and technologies to make them shine brighter than they ever did, and brighter than so many other contenders that don't deliver the full, broad, complete parameters that Thiel brought to light. I hope to conjure those last ineffable nuances of music. Love is a personal thing.
So my reason for loving the 3.5 is personal. I was intimately involved in its development, parts sourcing, voicing, manufacture and tweaking. Those 3D baffles were all hand-carved by . . . moi and an assistant, in an amazing hand of man effective method . . . and then tooled on a vintage inverted router (souped up with an 8" diameter forming tool that I designed. You get the picture, full frontal engagement. The fiber (silk, paper) upper drivers do not have the resolution of metal, but they are more forgiving. The woofer was our first polypropylene and we custom designed the cone profile for significant breakup improvement. The caps in the 3.5 were Solen when Solen was using their own best-in-world French film. The micro bypasses were 1% styrene x tin foil. Lots of tweaking and voicing and audiophile sensibilities. Later products lost that last level of detail due to cost / value engineering. There just wasn't enough improvement for the considerable extra cost. Also the newer metal drivers changed the cost / performance equation again and caps suffered - inserting a little vague jangle, in my opinion. I have always locked on bass authenticity from my musician and recording days of youth. The 3.5 sealed bass has a rightness from the very bottom that just doesn't quite bloom with reflex bass. OK, the reflex bass hits all the adjectives better - tight, punchy, etc. and plays more than twice as loud. But the sealed bass of the 3.5 and 5, digging lower than the recording, somehow lights my fire more naturally.
To your question. New Thiel models and generations always mitigated the problems of the previous generation and improved everything they addressed, within the limits of balanced performance. I think a newer, bigger model would almost always please more people more often. Try to audition some.
The gist of my quest is to resurrect some of the old models which can be had at bargain prices and apply lessons and technologies to make them shine brighter than they ever did, and brighter than so many other contenders that don't deliver the full, broad, complete parameters that Thiel brought to light. I hope to conjure those last ineffable nuances of music. Love is a personal thing.