Thank you both for your prompt responses.
@lewm Your (1)--isn’t that cartridge overhang? I did check that with the cartridge alignment tool provided with the ET-2.
(2) You are correct about the type of level I used, so I just rechecked it with an 8" linear level, and it looks good in both planes.
(3) The ET-2 has a horizontal mass of 30 g, vertical mass of 7 g. I guess as the arm traverses the platter there would be some slight effect, but the benefit of the vacuum hold-down of the platter (and benefits of the turntable suspension) is probably more audible and worthwhile, in my estimation. Most mildly warped records (talk about "relative motion between the stylus and the platter"!) can be completely flattened, and such warps probably have more of an effect than the turntable suspension. The hold-down also reduces resonances from the vinyl. Physics is not my strongest subject, so I’ll admit to some handicap in evaluating such things. Generally, playback of music has always sounded great, and I haven’t noticed a systematic decrease in audio quality at certain points of most records, which I imagine would be the issue if there were serious effects from the interaction of the linear arm and the SOTA suspension. Also, the HFNRR Test Record has the same tracking tests at disparate points on the record, and I can check that the distortion is the same with all of them.
@stringreen Thanks for your offer, but I’m quite far from AZ. But also curious what a Fozgometer is/does.