DTA-s have a dyno box with two potentiometer knobs for fuel and ignition advance, and button to save tuned values for the chosed cell of tables. And the interpolating is switchable off, when Ecu use the nearest cell values.
Any similar feature and cheap device would be fine for dyno mappping.
http://www.dtafast.co.uk/Downloads/Manuals/S%20Series%20Manual.pdf
I have found the 3D tuning maps in Megatune VERY quick to tune on the dyno. My dyno man just looks atthe screen at to find the throttle position relative to the map holds it there while I increase or decrease to bring lambda in line with target lamda, giving time to verify the readings, then move on to the next point. I managed to map all the points from 2k up to 5k in less than half an hour. After that we tuned the full throttle points only and extrapolated the rest.
I have yet to try any 3d tuning in Vemstune, as it needs an amount of re learn on my part.
On subject
I would like to see, to name a few
At least one expensive Misc output (as in 1.1.47)
Simple engine check output (similar to 1.1.47)
Second wideband chanel for monitoring ONLY
Configurable delay power off function for electric waterpump and fan run on (similar to fuel pump control)
PWM electric water pump 'temperature' control
And for an exoctic release, siamese code in a similar vain to latest megasquirt code.
I think that is about it