I have GS-5 and G-belt sitting on top of D-box platform. A very pleasing combination.
I can get all three working in most games that I play.
Forza Horizon 5 requires a fiddly workaround that must be applied each time the title is launched. Not the worst thing ever. I'm very glad to have it working.
However, I believe the setup could be perfectly smooth, and allow the advantages built into the SC4 launch options.
I believe what would be needed would be to direct SC4 to listen on a different port than 10001.
For this title, D-box listens on 32000. As far as I can tell, I can't change that. (Lack of customization has always been an important drawback of D-box's closed system IMO.)
But If I could direct SC4 to listen on 32000, I think that would settle things.