Remember First Glasgow also took on McGills with their 901 and 901X services from Glasgow to Largs in 2008. First were using 07-plate distinctively branded B7TLs with the 901X cutting out Greenock town centre and instead running along Drumfrochar Road. The First buses were more prone to random acts of vandalism in the Greenock scheme than McGills, I believe...
As for McGills 904, it’s usually the domain of very tired Citaros and B7RLEs and I’d say at least once a month you’ll see one waiting for a recovery truck in Largs.
I bet it wasn't the local youths carrying out the attacks on Firsts vehicles in Greenock either....