DVD43 doesn't care if the drive is RPC1 or RPC2 - at least, I think that's true.
The ways to escape from the "big brother control freak" of region coding are many.
From software that bypasses it, like DVD43 and ANYDVD,
RPC2 Autoreset drive hacks (some NEC firmware hacks).
RPC1 (regionfree) drive, plus software de-regioning, is actually a rather old method now - the "all software" method, and particularly a free version of the all software method, means it is no longer necessary to hack drives.
It is CRITICAL to note, just RPC1-hacking a drive is not good enough, unless you are happy to let software region controll require that you reinstall the sytem every time you use up the changes.
The other approach, which I believe LTNRPC can do, is to make uncounted or reset changes on the drive (just make sure it's not draining "vendor resets", or you'll still run out!).
If your software works with DVD43 (the only real point against it is that it can be a bit iffy with some programs), then I'd leave it at that.