As far as your comment "AFAIK, MD accepts any pistol from the CA and MA rosters, too?" MD doesn't "accept" anything based on other states, it evaluates models independently by a board (only models made after Jan 1, 1985. Older models are not subject to the MD Roster as long as they are not banned by name). It also has a list of banned and "assault pistols" that are not allowed to be transferred in the state (e.g. SP89). The MD Roster historically was designed to keep cheap "Saturday Night Specials" off the streets. Things like Ravens, Davis Arms, Cobra Arms tend to not be approved on the roster because of safety issues related to the alloys they are made from, and guns like the excellent NAA mini-revolvers are disallowed because of lack of trigger guards. Anyway, the roster has been used as a tool to stifle arms possession in MD. Right now, however, the attitude of the handgun board is 'give us a reason to disapprove the gun' so things have been getting approved nicely since our new Republican governor took office e.g. SP5K, Omega OM9, numerous AR15 pistols (even though many DI AR models are banned in MD), numerous AK pistols (even though AKs are banned in MD). But they still routinely disapprove guns that don't meet the legal safety requirements such as lacking a trigger guard. Approval by the Board is pretty easy. Fill out this form
and provide a sample of the gun to the Board to review (they do not shoot it, and they do return it). As I noted earlier, variants don't require you to submit a sample, just a form (so I was easily able to add the SFP, P8 and P10 to the roster). Color variations are not considered variations requiring approval and neither are sights. Lately they have been liberal with caliber variations too. For example, you don't need to submit a sample for a caliber addition and some guns (e.g. HK VP) were approved in 9mm, .40 and .45 even though the Board only reviewed the 9mm sample.
I have to say, if the only HKs on the CA roster are USPs and P2000s then soon when those legacy lines stop being produced by HK (IF HK chooses to stop paying the $200 annual renewal fee) CA citizens won't be able to buy any HK pistols. Is that a correct assessment (excluding mil)? I'm assuming P7s are not rostered simply because HK doesn't pay the fee for them anymore...