What kind of environment? I never played Mass Effect only Deus Ex:Human Revolution, but from what I read top weapons Shephard takes out Jensen due to better tech, but if Jensen gets close Shepherd is done for, considering the weapons and upgrades in here, I'd say Jensen gets his cloaking, smart vision and radar if he's in a complex or urban area, silent mode gets behind Shepherd and tears his head off with the blades, even if Shepherd has ways to get across the cloaking and silent mode, a machine gun and handgun aren't bringing down Jensen easilly before he gets close and personal, not with the speed boost and armor plating.
Then there's also typhoon that will mess up Shepard if he get at mid to close range.
Shepard had help with the Shadow Broker. Shepard's tech powers wouldn't work that much on Adam, IMO. He gets his own biotics (although I know he can learn some from teammates). They fight in the Arena. Shepard has shields, but Adam is more durable due to his cyborg parts IMO.
If they have full upgrades, that means Shephard has his fire, ice, drones, sentry guns, stasis, etc. at his disposal. That's too much for Jensen. Shephard only had Liara on his side against the Shadow Broker, and she didn't do much.