I dont know if the Timing is more aggressive on the Edge Drag Comp Vs. the Edge Ez.
But many users like Rob Thomas have an HO engine with the TSTPM3 Comp and Edge Ez stacked on top of it.
The Timing of the Ez adds a nice bottom end to get you going, as far as too much timing? Maybe, maybe not.
But, one thing else to consider is modifications to the VP44 shorten its life span, typically.
Also modifications and severe additions of power to these ISB's also shorten the lifespan of the engines bearings and wear surfaces (ie bearings, pistons, crank, cynlinder walls).
So if your worried about breaking things, dont modify.
If not, go for it (stock is no fun).
I have a friend who ran a Custom Comp with heavy timing for over 40,000 miles with an HO motor.
He never blew a head gasket.
As said before the Drag Comp will hold its own with the TST Comp/Ez combo.
What it really comes down to are user friendly features, if you like the advantage of 10 levels vs 5, also electronical gauges provided with the TST unit are nice.
The Edge box is more basic, but works really well (ask Jetpilot)
Good Luck!
--Justin