Am I stupid for considering passing my DAS in July and jumping straight into something like a BMW 1250RS? Sure it's not a flat out sports bike but is still a big bike, although quite easy to ride going by reviews and it's CoG is quite low down being a boxer engine.
Not especially stupid . Personally I'd suggest if you are mature enough (I forget if you mentioned your age previously), and have been driving a while in something not ridiculously slow, without constantly crashing into people, losing self-control, or accidentally reversing into a gaggle of nuns and then faking your own death and leaving the country in the back of a horse van, you might well be just fine. But you'll get as many for as against on this topic, generally.
The R1250RS is a friendly enough bike and with its engine braking is very forgiving. I'd suggest if you want to allay your own concerns, or those of anyone you care about, smash on a few riding courses after you pass, such as CSS, which will add a great deal of useful tools to your riding... bag.
I rode for years before doing CSS and the BMW ORS, and combined, plus riding with people far better than me - and not being stupid - my riding has come on a massive amount in the last few years.
I went SV650, F800ST, K1300S, K1300S, S1000RR and R1250GS, then KTM1290GT and CRF250. Couple of years or so with each bike.