I went from an IR flash for my manual to a quartz flash at the begiining of this year and would not want to go back. First it is incredibly safe, if you have to walk away from the press there is no worry about burning a platen. Second the consistency, no worry about over dwelling a shirt, very helpful on nylon and poly that can shrink with too long a dwell. Then there's the fact that there is not heat-up time turn it on when your ready for the first shirt and go.
As for efficiency, if you are a small shop and wear all or most of the hats it takes to run a business like ours, there is no doubt in my mind a quatrz is more efficient than IR. It is very rare I start a job am not pulled away from the press several times before the job is finished. If you end up away from the press the quartz just sits there idle, the IR keeps crankin no matter if your at the press or not.