I don't really get the MkVIII thing.. having the same engine and same boost as either the MkIX or the XVI, it won't be any faster, won't climb any better, won't turn any better, and probably won't roll any better neither.
Basically it's the same plane three times, with the same performance, the MkVIII having more fuel capacity, which is great, but not in a flight sim... it's really a waste of development capacity,unless the MkIX stays as a IXF `42/43 one with Merlin 61 and +15, the MkVIII would be the LF version of 43-44 with Merlin 66/+18, and the Mk XVI being the 1945 on with some improvements and +25, which would make it a counterpart for the G-14 as a latewar free ride...