Bob, glad to hear that your enjoying your new toy. You might want to get a "bug deflector" so as not to collect too many mosquito's on that shiny chrome "bumper" though : )
As to my comments about the old Perreaux's, i believe that they had two different "family sounds" within the same product line. The 2150's sounded different ( somewhat hard and forward ) than the 3150's / 5150's ( these two were MUCH warmer and smoother with OOMPH on the bottom end ). There were also the 1050's and 1150's with one sounding like the 2150 and the other sounding like the 3150. As you noticed, i was not familiar with the newer stuff and stated so in those posts.
From your initial comments, it sounds like the 350 is closer in sonics to the 3150 than to the 2150. As such, i totally agree about the "slam" factor and bass impact. The 3150 also lacked "air" and seemed somewhat "closed" in terms of the sound stage. I had tried these amps with tons of different speaker cables, preamps, etc... and had always come away with the same impression. At least they were consistent and you knew what to expect.
Then i tried my pair of 3150's with some YBA Diamond speaker cables. WOW !!!! I had never heard them sound so open and detailed. My girlfriend was EASILY able to tell the difference between the YBA's and some other cables that i A/B'd for her. Yes, the sound was slightly thinner but the high end actually sparkled and shimmered. Since the speakers i had them hooked up to were already on the warm side, this was a welcome change. Given the tonal balance of ones' system, the added brilliance that the YBA's brought with them might be too much of a good thing though. In other words, keep mixing and matching speaker cables. There is SOMETHING out there that will "blend" the sonics of the amp with the specific speakers that you're using.
For comparison sakes on your end, my 3150's are biased Class A up to appr 50 wpc. Needless to say, they run HOT, HOT, HOT. Idle temperature at the top of the heat sinks is probably about 150* F, give or take. When hitting them hard with no air conditioning in the summer, touching the heat sinks WILL burn your hand. In terms of them "running out of steam", i have been able to do that with some of my less efficient and low impedance speakers. With your speakers, they should coast at a just a few watts most of the time, even when getting on it.
As to popping your speakers, it is possible but not probable. They do have protection built into the tweeter circuitry. You might want to keep in mind that the original manufacturer no longer makes replacement diaphragms for your drivers though. If you really like those speakers, you might want to think about hoarding a spare set of diaphragms or two.
I ran an amp that was doing about 375 wpc into my "ugly" version of your speakers for extended "jam sessions". Just to see what they could do, I clocked SPL's at a steady 117 db's on AVERAGE at a listening distance of appr 10' or so. At this point, i think that the amp was running out of steam, not the speakers. While these speakers are supposed to be capable of 128 db's according to the factory, i think that they are talking peak and at 1 meter. Either way, you'll either be deaf or divorced if you try to find out : ) Sean