Hell no, would be a great challenge- just means you have to work a bit harder. the harder (if that's the right word- busier maybe?) grades (ie jobs) get paid more anyway- and its only fair that the guys who HAVE to work harder get paid more.
Bear in mind that every unit has its challenges and the work load at Heathrow could be argued to be just as high as at Gatwick - which holds the title of busiest single runway airport in the world, and the ATCOs there have to work very hard especially in peak times to maintain an expeditious flow of inbounds and outbounds on just one runway - whereas at Heathrow I believe there are several ATCOs working the aerodrome controller position, so less workload individually, as well as Heathrow no doubt being at the forefront of new equipment, making the ATCOs jobs there easier, which may take a while to be introduced to less busy units.
It is similar to the London airport approach/director positions which are all a LTC at Swanwick - Heathrow, Gatwick, Stansted, City and Luton. They are all band 5 pay (top of the scale), yet City and Luton are much quieter than LHR and LGW, yet get paid the same.....
