The G250 HP has to be subdivided in to an A and B configuration.
The "A" configuration is basically the "old" G250 design utilizing the new and improved S wing poppet design and a modernized adjustment knob. It has a slightly different balance chamber than the G250 to accomodate the slightly longer poppet assembly.
The G250 HP "B" configuration also uses the S wing poppet but has the adjustable balance chamber used on the S600. When peopel talk G250 HP they normally are meaning G250 HP "B" configuration. The seat saver feature has been dropped on all of the SP regs and so the older G250 HP B's will have it and the newer ones won't.
The old Adjustable and Balanced Adjustable regs can be upgraded with the new poppet, balance chamber and spring to near G250 HP "A" status in that they lack only the VIVA adjustment but none the less breathe exceptionally well with a very durable smaller profile metal case to boot.
I don't think the G250 HP "B" configuration breathes all that differently from the G250 HP "A" and is in fact potentially an even better performer in that it is just an oversized S600. But the "B" configuration does require some additional tools to adjust the balance chamber properly and this may lead to less than 100% performance if it is not done correctly.
SP is ditching the seat saver feature and along with it is changing the balance chamber design to eliminate the need for a special adjustment tool to seal off the end of the balance chamber. The new design will allow an air on adjustment with only a screwdriver - much easier for the tech to adjust properly.
Incidentally, the G500 came in a US produced version which was exceptional (ID = all black purge cover) as well as a later european produced version that was not as good a performer (black and grey purge cover) due to being detuned a bit to meet european standards. But the good news for euro G500 owners is that like everything else scubapro, they can be upgraded, in this case to S600 status.
