I always fly at "odd" levels e.g. 4300ft, 3300ft, etc.
I understand why you would do that in class G, so if talking to ATC giving you a traffice service in class G , and you were in cloud, on a UK IMC you would report when checking in blah blah level 3300 IFR ?
Would that not be technically incorrect and they may question your altitude?
And then when you were ready to request the transit of say SOLENT you would presuambly want to be at an IFR level correct with semi circular rule?