is the Plycounter still legal to use in a tournament?
Yes according to the bottom of this document: http://www.uschess.org/docs/gov/reports/eScoresheets/CertificationGuidelines.pdf
Under US Chess rules:
Yes if the organizer does not specify a standard scoresheet and require its use.
Yes if the organizer specifies the Plycounter as the standard scoresheet for the event.
No if the organizer specifies a standard scoresheet other than the Plycounter and requires it’s use.
There will likely be folks chiming in here that the organizer must announce a standard scoresheet in advance, or must allow a player to use a second scoresheet. These folks are simply not correct.
No, there probably won’t be since that subject was thoroughly discussed on another thread or two. Suffice it to say that not everyone agreed with Mr. Price, but absolutely no one changed anyone else’s mind on the subject. Hopefully no one will redouble their efforts.