Hi 66DN,
I debated the same as you back in the day. I decided to go with what you call "Heavy Duty Standard." Mine are NOT the "Comfort" version. The front shocks these Bilsteins replaced failed badly at the top mount area. I was worried of introducing a more rough ride with the heavy duty Bilsteins but took a leap of faith based on reviews. In the end, I am extremely happy with my choice. The change in comfort with regards to harshness is truely negligable but the improvement in front stability was tremendous which increased comfort in other ways.
If you have not found my write-up on this subject, here it is for your convenience. It includes many pictures.
https://forum.phoenixusarv.com/index.php?topic=3580.msg30529#msg30529A change of subject here, but it is somewhat related. Check it out. You might do good, or you might do bad from doing something similar. I changed front coil springs to soften my front ride. I DID NOT do it because of my choice in Bilstein shocks. For us with our PC's load and load distribution, I would have done it regardless of the shocks installed.
https://forum.phoenixusarv.com/index.php?topic=4168.0I feel I am in a very good place with the ride and handling of our PC, but..... I have one more matter to look into that is related to my Safe-T-Plus's cantelevered mounting bracket. The pressure applied from this extra long bracket, on the end of our E350's frame where it mounts, is slightly twisting the end of the frame. I believe that slight twist introduces a little of "the floaties" in the steering wheel. I will look into strengthening the E350's "C" channel frame there via bolting on more steel.
Since the E350 chassis has a slightly thinner gauge "C" channel chassis frame than the E450, I would assume people with an E450 see this less of an issue, or it may be non-existent.
Ron Dittmer