[Thessaloniki X City Configurator [v3.0] (if you have OOM issues)]

OK, what I'm going to say won't contribute to the solution of the PMDG/LGTS OOM problem, but I think the way to go for the foreseeable future (until the advent of a Prepar3d-64Bit that is) will be to do it like the folks at Majestic did.

They wrote (or purchased) their own simulation kernel for their Dash8-Q400 which they run outside of FSX. They use FSX simply as their display engine, nothing else, and have a very basic flight model that resides inside of FSX. They don't use this flight model but rather move their arcraft in slew mode from outside of FSX.

This way, their aircraft simulation can be as complex and memory-consuming as they want it to be, and it doesn't add to FSX VAS. The only parts of their code that uses FSX VAS is what is needed for display of their panel/VC and the looks of the aircraft. Rather clever if you ask me. PMDG should take a closer look at this technique for their future products.

Just my 2 ct.