Re: Waves multitrack & Soundcraft SI consoles
While I have not personally set it up, I have had the opportunity to play around with the impact desk.
It has 22 inserts available and you're able to using the full console routing to get in and out of them. (Minus the XLR in preamps.)
Over all, the Multitrack integration is far superior to the X32/M32 setup. You can actually route busses and your LR through Multitrack. You also retain control on your head amps on the channels.
There is no reason why it wouldn't work, however I'd suggest looking at a MGO and Soundgrid server. That would essentially give you 22 insert points and 42 channels of record/virtual soundcheck.
The routing and flexibility on these desks is excellent.