I have worked on a few of the newer M-7's with the modified truck, and to be honest, while they sway much less than the unmodified M-7's, the ride still seems to be a bit rough. Now instead of swaying like crazy, they feel more like a rough rider, or what I call a wobbeler. That was my opinion on it, and my engineer thought that it was riding a bit weird as well.
On a side note, I have seen a few times recently a few MNR M-7's around the property. In fact, last month while heading on an eastbound on line 4 around Kew Gardens, I happen to notice an adjacent M-7, (moving east as well) on line 2, with one of it's doors open!! It caught my attention big time as I thought that it was another train with an unknown door open enroute. As I kept looking, I then saw the Metro-North logo on the body. I believe that it had 4 cars on it's consist, and it was not being pulled by any other unit. While Merto-North's third rail is not compatible with the LIRR, their trucks probably were modified to fit ours to do a test run over the LIRR. The side of the train were filled with a number of wires that were running from the open door down to the undercarriage of the M-7. I'm not sure why these units are operating on the LIRR, but my guess is that they are being tested by Bombardier folks out of the HSF. I'm not even sure if these trains are running with a roustabout crew.