Again,just one's personal experience(all with CC 85HV):
35Mhz-no filter-occasional ,short, fail-safe episodes.
35Mhz-filter -no fail-safe episodes.
2.4 Ghz-no filter no problems(only thing -had one dodgy motor battery which would drop below the progammed 30V low cut-off and the CC "simulated" the fail-safe low throttle)
All the above with pretty standard F3A electric set-ups.

Just one other observation-not my scene, but there are quite a few electric helicopters in my club there were so many glitches on 35 Mhz,whatever else was in the radio set-up, that almost without exception, all the flyers changed to 2.4Ghz which solved the problems....