I don't think I disagree with ANYTHING that has been said here.
The things that are being said by newbagr have been said at LGW for the last 11-12 years.
BA saw the opportunity to change the crew agreements when they bought Dan Air, and they did so. Saving BA lots of money.
If you think BA doesn't want to do the same thing at LHR, think again.
Come T5 lots of the old agreements will change and be renegotiated. E.g. CAT turnarounds. (There won't be any!) So the money on EFLHR is going to change.
It has already changed as well (which not everyone there will tell you about), in that the allowances at EFLHR are now taxed at 40%. (20% at WWLHR).
Wit relation to the disparity in money, the allowance system which is opperated at LHR is a hangover from years gone by. It's only a matter of time before it changes (and everyone knows it if they are honest with themselves, the pilots have already changed to the hourly rate).
LGW is the template BA will hit the unions over the head with saying "Well they can do it cheaper and with less crew down there, you can do it up here."
The unions had their chance to negotiate up the pay and the agreements at LGW and failed (because they were too busy in-fighting between themselves and the other union).
I know the cost of living in the SE is high, the money has got better at LGW (I know I've been there for nearly 10 years), others have managed to live just fine on it and buy houses etc etc, and with us doing the WWLGW routes the money is only going to get better due to having more longer trips.
If your not sure if it's for you, and would much rather be at LHR for WHATEVER reason, then wait for recruitment to start there again. Simple. No one will think any worse of you at BA, and if it makes you happier, then why not!!?
You could always stay where you are and ask to swim around in the holding pool for a while. However don't forget every course that trundles through LGW your seniority number goes down and down and down until YOU start, and at BA seniority is everything.
What I would say is that don't judge it until you've tried it (you can always leave). If money is what you want, then go to Easyjet or some of the charter ops where you can earn great money every month. You will work for it mind you, a lot harder than you would at SFLGW, but if money is your biggest motivator then that would be the best option.
That's it in a nutshell, the choice...is yours.