Andy 2, I dont think I can add anything new to the many excellent threads discussing the trade-offs between SET and push-pull designs; and Im confident that an archive search will provide you with a plethora of information.
Tube preference is a separate issue, IMO. I like the 300b tube and it would be my tube preference in any design - money not being an issue; and there, I believe, is the rub. The best 300b tubes are expensive, and are more commonly used in SETs because only a single pair is needed. I used to dream of one day owning a VAC Renaissance 140. Given my current taste in 300bs, re-tubing would be cost prohibitive.