I've had the auto in my WH altered via the tune a couple of weeks ago- I had the line pressure increased and firmer harder/faster shifts whenever the Power button is pressed. In standard (non-Power mode) the shifts are still soft. Also had the PCM modified to kick down earlier than stock. This gives a more willing feel to the car overall.
Its pretty awesome. The fast downchanges are great for overtaking when you need it.
Also had the semi-auto function added so it will hold 1st 2nd or 3rd when the stick is moved into that gear, and will hold the gear to the limiter without shifting up.
One of the best bang for buck mods you can do to the 4L60E in my opinion is a shift kit or PCM edit, as the increased line pressure and firmer shifts means the clutch packs grip quicker and do not wear as fast as in standard slow shifts- firming up the shifts actually increases transmission life. This is why many USA taxis used to get the old "B&M Shift Kit" added back in the day- taxi operators knew that less clutchpack slippage generated less wear and heat and the trans life could be extended for a few years extra- important cost savings across a fleet of taxis (imagine replacing 6 auto trans in 6 taxis in 6 months..)
I would not add a mechanical shift kit plus a PCM edit at the same time though- you may end up with too much line pressure in the valvebody and blow something. I would always get the PCM software changed, and add mechanical "helpers" like stronger accumulator springs.
I've been informed our LS 4L60E already has the Corvette servo gear inside them- so that may be fine to stay as is.