Tim,
Really good question. For me it comes down to trust and time. Like many on the forum, I have a busy life and thus time is at a premium. When I go shopping, particularly for something as important as a bat I need to feel that I am making good use of my time to get a quality product. Now whether this is to go and have something made bespoke or to buy an off the shelf the next choice for me is focused on trust.
The last bat I purchased came from Asad at Uzi. I know I will be slated by some, but it was an MC LE Spartan that was advertised on here. I know he went to the warehouse to hand pick the bat and I know he went through the (majority of the) warehouse's stock to find that tranche of bats for his store. I appreciate the warehouse is only a snapshot of the total Spartan range and that Asad's hand selection has further reduced my total customer choice. However, from what I have seen on here and how he has dealt with me personally... he has my total trust.
What does this mean, I know his hand selection reduced my available options but balanced against my time available, I believe he has helped save me significant time by conducting the initial weeding out process to focus on quality products. Though I freely admit this is a subjective assessment. I am sure other shops offer a similar service but I have trust in Asad and his handpicking process has given me great confidence in the product.
Is this relevant for a brand like GM? Possibly not, if you truly believe an item like a cricket bat offers uniformity but it does, in my mind, create the concern of shot gun supply chain with an element of the personal touch removed. However, I think GM is a first class brand and have happily used their bats in the past. When I purchased, rightly or wrongly, the MC LE did I get the best one in the UK? Almost certainly not but I gained confidence from Asad's selection, personal service and then my fumbled waving of willow and tapping up in his first class store.
In conclusion, if you have faith in the person doing the hand selection (this might be misplaced but certainly helps my batting confidence in relation to a product - surely this can only help your game) then it can save you precious time and lead to a good buying experience.