Hi,
I've been at different sites and threaded mode turned out to be faster or at same speed in nearly all cases.
It is very important to have an understanding of the pools. A wrong configuration is more a problem than in process mode. The number of threads in each pool should not be configured too high.
Some values of your current monitoring will not be useful anymore. E.g. higher values for "i/o busy" in sp_sysmon. This is because i/o tasks are not engine bound anymore and not only one engine checks for outstanding i/os. Now more threads are doing this leading to higher values of i/o busy but there are not more i/os.
Best regards,
Juergen