I agree that the speed with which the VSL software is adapted to M1 is disappointing however they are certainly not the only company having problems getting their software adapted. Apart from Kontakt all Native Instruments soft and Hardware still needs Rosetta.
Do you really have such big issues using Rosetta with Dorico? I am running a Dorico 4 project using Rosetta with 70 instruments in the VST rack, 49 VSL Synchron and the rest BBCSO and a few Kontakt Percussion instruments. It takes bit of time till the project is playable but I have no big issues when it is ready to play. Sometimes a few clicks when 2 or more instruments are played at the same note for the first time in a session (a CPU peak). You also see it very well in the Logic CPU monitor. When you play it a second time there is no peak nor clicks.
Before my M1Max I had to use VEPPro for this size of project as I had only 16 GB on my Intel MBP but with the new M1Max and 64 GB this is not needed.
I did test VEPPro with a similar size template but only with Logic (so no Rosetta needed). The main reason at the time was that the Synchron player did not work directly in Logic whereas it did work when accessed through VEPPro. Now the Synchron Player works directly in Logic.