Sealink, don't worry. Basically, the "hard product" (i.e interior, PTV's etc) aren't as good as many of the LHR machines. Last year I flew a sector on a A343 (that has a similar hard product to LGW aircraft) and it was fine....infact it was an enjoyable flight. It's just that the LHR aircraft are actually very well equipped and so the difference between the two is very noticable and it's taken them a while to start updating those ar LGW/MAN. Put simply, the product on your aircraft, in Economy atleast, will still be leaps and bounds ahead of some of the other carriers you could have chosen to LAS.
The actual inflight service is very similar if not identical and the crew operate both LGW and LHR so there is no "second tier" crew mentality. Even if there was, you can still have bad and good crew regardless of airline or base.