We have high expectations for velocity.;)
These haven't been chrono'ed yet, but the 11.5" should be similar to a normal 12.5".
Larger 5/8-24 threads are stronger and better, especially when suppressors are involved.
Any 30 cal suppressor will work and quite a few 5.56 QD suppressors have 5/8-24 mounts available for them.
The 5/8-24 SilencerCo ASR Mount works with the Specwar 556, Specwar 556K, Saker 556, Saker 556K.
The 5/8-24 AAC 51T mount works with the M4-2000, 556-SD and Mini-4.
The 5/8-24 Griffin Taper mount works with the Reece 5 and Optimus Micro w/ optional taper mount interface.