Tom in your eyes as a former big wig and i know you have done reaserch and what not is there a big difference in bats
There's (No Swearing Please) bats in all price brackets. Some bats just don't turn out very good. You can spend £300 on a the best reviewed bat from a reputable retailer, and it can be a plank.
Every company wants to make the best performing bat they can, whilst retaining a unique marketing aspect to sell as many as possible. There isn't a huge difference between a top GM, GN, Mongoose or anything in my view. The finish on one may be better, the stickers may be better on another but beyond that there's not much.
As for pro bats - I never really saw one bat on the circuit which made me go wow. This is a special piece of willow.
My advice is always the same, go to a shop, choose a bat which you like the pickup and feel of. Knock a ball on a few. Some of you may also have a batmaker who you trust, therefore negating the need to visit a shop. I'm in that boat, I trust TK and Sareen to make my bats.