So the geometry of the PLX arm doesn't match the geometry of the SL-1200? I thought they would have copied it for simplicity, and also the LP120 matches the geometry of the SL-1200 from what I've read.
The geometry is the same but the stock headshell shipped with the Pioneer is apparently shorter and optimized for the Stevenson alignment. Most folks around the net who've bought PLX-1000's have mentioned ditching it for a better headshell. Event he Ortofon SH-4 headshell reportedly provides better alignment potential and the azimuth-adjustable headshells available from LPgear or Turntableneedles.com (among others) provide all kinds of adjustability.
Plus it depends on the cartridge, or rather the distance between a cartridge's stylus tip and mounting holes. I had a similar problem with my Pro-Ject Xpression only in its case, you can't change the headshell as it`s part of the arm. When I used Ortofon 2M Bronze and Black, the slots in the fixed headshell weren't long enough to achieve a Baerwald. Once I moved to an AT-OC9MLII, I was just able to reach Baerwald. Then I switched to a Denon DL301MKII and using its long slots instead of mounting holes I'm able to reach any of the preferred alignments (although I use a customized Lôfgren B to reduce high the end-of-side distortion inherent in a standard Lôfgren B).
If you read through the entire thread, you'll notice some inconsistencies. While the OP is to be commended for taking the time to try out the Pioneer, it would have been nice had he tested it properly (using a test record for antiskate for example), realized that lots of turntables have issues with Grado hum (including some versions of the the SL1200é1210 according to the Grado hum database at vinylengine) and stuck with his story (first his antiskate was inadeqaute, then it was not working at all, now it's back to inadequate; first he was barely able to reach a Baerwald, now it's not at all). Plus he may have had a bad unit since his implication that one cannot use a brush to clean the records due to low torque is just not at all borne out by any other comments from folks who've actually tried the PLX-1000.
Look I have no boat to row in this argument for now as I've put off my turntable purchase for awhile, but I'd love to see some consistency and proper testing in such an effort. If you read around the net for all the comments from folks who've tried the PLX-1000, there are a couple of issues that come up, specifically that in some cases the arm bearings are not quite as tight as they should be but a very slight turn of a screwdriver seems to fix that, that the stock headshell is limited to a Stevenson alignment, and that some folks find the antiskate to be weak (yet others claim theirs is fine). Is it as good as an SL-1200? In some cases, it's better, such as the ability to use your own interconnects, and the anti-resonance treatment inside the tonearm. If Pioneer had kept the Technics SL-1200 in production and not raised its list price any further than the May 2010 increase to $899, it would sell for just under $1000 now and we wouldn`t be having this discussion. They didn't and it's highly probably the new Technics turntable will be aimed at a super high end market like the other new Technics components, so if you want a new, warrantied turntable with direct drive, on-the-fly VTA and removable headshell, the PLX-1000 is most likely the best candidate under $1000. I recently asked the dealer where I bought my Pro-Ject to give me the best option he carries with on-the-fly VTA and removable headshell (I didn`t bother asking for direct drive since he doesn't carry anything non-belt). It was an Avid Ingenium with SME M2-9 for a bit over $2100 US. Plus in researching the M2-9, I discovered that not only is the headshell a custom design that's about $200 each, it has fixed mounting holes so if you like to customize alignments as I do, you`re out of luck! Plus there was that Fremer review of the Avid in which he talked about some speed issues.
Sometimes digital seems so much easier! I just wish it sounded as good and was as much fun as vinyl!