Deepdale Road does a fair bit of prep & repair work for NW ops, Rotala have been using Go Goodwin's opposite (DBNW Eccles base) for engineering work with Citaro 33001 & Trident 40596 being repaired by them.
They don't keep sending damaged buses to Avonmouth, they don't normally do repair work for the rest of the group (must of had spare capacity), they used to send accident damage repairs to Rotala HQ at Long Acre & now Tividale Group HQ.
I don't really see D&G being that attractive to Rotala, especially as the majority of their routes operate within Stoke, which if the bus operating territory is as bad as First Potteries state, just not worth it. Don't forgot D&G are also linked with Midland Classic.