I agree with some of what you are saying - I agree on the state of the LGW planes inside for example, and lament the demise of the newspaper selection at the gate at LGW.
Not sure I agree on security though. LHR T4 and LGW N can both vary widely in terms of security wait. I've been in "Fast Track" queues at T4 that stretched well out into the check-in area before now, and took close to 25 minutes to clear. At LGW I rarely find myself queueing for more than 10 minutes at security. Fully accept this may be down to my travel patterns and that others may have different experiences. I certainly wouldn't choose LHR T4 over LGW N on this basis.
As far as breakfasts go, I thought the CE hot breakfasts ex-LHR and ex-LGW were pretty similar? Can't imagine them specifying downgraded food for CE on the LGW flights ex-AMS compared to their LHR cousins - differentiating like that would surely increase rather than recuce overall costs?
In terms of lounges, LGW isn't bad at all. Certainly I tend to find the Terraces more peaceful there than at LHR, and the First lounge is generally pretty tranquil (unless there is an FT Do in progress of course...).
On board, to me so much depends on the crew. The most regular route for me from LGW would be to LUX, a short flight with half the passengers typically in CE. The experience has ranged from brilliant to underwhelming in terms of service. I have been a bit concerned that some of the staff downgraded from long haul only to the mixed fleet staff are annoyed and don't go the extra mile as a result.
The real issue that needs to be addressed (and this is as valid at LHR as LGW IMHO) is the variability in service standards on board. They should start using "mystery passengers" to monitor what happens on flights rather than relying on the on board surveys.