The extra buoyancy is only needed to offset the weight of the gas and that's very little when using a single tank like a 10l or 12l. I use the bc for 2 or more tanks but not for one, no need to as there would be hardly any gas in the bc anyways. If you have a large bubble or find it hard to manage you must be diving overweight.
It's actually easier for new divers to only use the suit instead of having to dump gas from to sources.
