I am not too sure if Luton have full Mode S for ground movements yet, but the days of validation of Mode C when airborne are possibly long gone? The only way to maximise R/T time when busy is to minimise the use of VHF. In 10 years time with datalink, VHF will be only used sparingly and as a back up. Massive leaps in ATC technology are happening. The theory is more automation makes handling more planes much easier.