Your comparing a diesel to a v6. There isn't a comparison. Diesels make all their power down low, and make an incrediable amount of low end torque.
If your looking for off the line power, your not going to find it in an engine designed to rev to 6500 rpm. The 6 doesn't even BEGIN to make power till 3,000, and really isn't zippy till over 4k rpm.
If you aren't willing to drive the car that way, then skip it, and look for a vehicle thats either a diesel, supercharged, or a v8. (Both giving alot of low end umf). No amount of mods for the 6 will forever solve the "off the line" problem. Its by engine design that its power is made at the upper rev's. You'd basically need cam work, engine retuning, or forced induction to solve that problem...Its just not worth it!
There is a computer update to address "off the line hesitation" in the v6 ATX's in the 6s, but thats not going to make it match a car thats been tuned to jump off the line.
Either get a manual, or go with the hyndai, or one of the above choices.