The choices I would recommend are not listed above. (And are not the ATC, which is huge expensive and just plain HUGE.)
I'm just not a fan of the Vifa PL's. Any of them. I don't think they're as good as the equivalent Vifa Classic Series drivers. Instead of the PL11, the M10 would be my preferred paper Vifa. This driver is strangely overlooked, but it's a got VERY good transient response and makes a nice midrange that by the standards of the very best midranges today is maybe a little darker. Less efficient but more detailed and even more liquid is Vifa's 10BGS. Honestly, I have no idea why nobody in America knows about this drive-unit. It's spectacular. In Europe it's probably been the best-selling hobbyist driver for the last three or four years running.
Also, why Aura NS4 instead of NS3? The NS3 has a better-behaved cone, would be less visually obtrusive, and in an A-pillar MTM who cares about sensitivity?
A midrange from another brand that I’d recommend considering is the Audax HM100Z0, which is on sale at Madisound and a fabulous midrange. (My all-time favorite midrange driver is the 130mm version of this driver, the old Audax HM130Z0. The 4” carbon midrange listed above is very similar to the midrange driver used in the excellent first-generation Von Schweikert Research speakers, but I prefer the HD-A cone to the carbon cone on the same motor.) It’s more tricky to work with than the smooth-and-linear-forever 10BGS, though. Also, Audax abandoned DIYers whem Harman Int’l bought them and made them in-house driver maker for Revel et al, so buy spares if you go with the Audax...
small midranges options A or B :) Vifa or Aura
Linear Mode
