Great report there. Happy to hear you had a nice time down at STN.
With regards to LGW having crapped, stuffy terminals, id have to say not at all. Theres no low ceiling in the south terminal at LGW, and its well lit and very airy.
Cant speak for the North terminal as i have never been in it.
LHR though on the other, dont get me started. Im in T2 and T3 everyday!