Hi Tai-2...

You can fly formation in any type of aircraft or types together. It takes practice, experience and training in real life.
The computer or at least mine is very sensitive to control so it is not hard to slip out of formation while flying on the computer.
The DeHavilland DHC-3 Otter is a light utility aircraft with STOL capabilities therefore very easy to fly in formation in real life with the proper training. Much like the old Harvard, Chipmunk and "T" Bird were.
We have actually rolled and looped the Otter with no problem at all. The original P&W R1340 was a little underpowered for the Otter and was the same engine used in the Harvard.
Sorry can not comment on the Turbo Otter as I never was qualified on them.
Cheers...Happy Landings...Doug