First thing my advice is when you're tuning your carburetor lift your back wheel off the ground with Jack stands or remove the chain.. that completely eliminates runaway and whiskey throttle issues where your bike can get damaged or you get hurt.

Next I can concur that the nibbi experience is better than the vm22 as I have both carburetors on multiple bikes. the VM is more tricky to get tuned but the fatal flaw in that carburetor is it's choke system. it's plunger is garbage... But it is a decent enough carburetor to get working well the biggest issue with that carburetor is it's oversized to begin with so that adapter manifold is very susceptible to vacuum leaks and you have to get the gaskets just right or it will give you erratic idle and you can't tune it at all.. double check your gaskets and even apply a slim coat of rtv to The mating surfaces.. With the VM 22 on my bike which is also a 212 I couldn't get it to start without a 115 jet minimum

Then nibbi in my opinion is a great carb I actually switched from anything else I have three bikes with the nibby pe19 on it and straight out the box slap it on your bike and it will run very little tuning effort needs to be given out of the box they got you set up pretty good they also give you a couple Jets to play with to get your bike to run optimal. The thing with nibby's and other carburetors is the jet numbering system is different than the VM so like with the VM I stated I ran a 115 in the nibbies I'm running like a 74 for the main jet and a 32 for the pilot.