I struggle to see how the variations in transition altitude make any difference. If ATC tell me to climb to XXXX thousand feet, I climb to xxxx thousand feet on the QNH. If they tell me to climb to FL xxx, I set 1013 above accel altitude and climb to FL xxx. How is that difficult? If you're told to climb to FL xxx and you then level at xxxx feet on the QNH you've almost certainly got it wrong!