My 9.5" 4k stall Dynamic is a great WOT piece and actually feels pretty nice on the street as well...but the throttle crispness I felt with the previous 2800 stall is long gone...wouldn't mind some of that back...and a fluid change is a worthy (and a fairly inexpensive) experiment!
I have a 9" Ultimate in my car, and it works well for the gearing and camshaft, I have no complaints but it definitely isn't crisp like a stocker. I was worried on nitrous it was going to change the stall speed too much, so I tried switching from conventional type F to ATI's 30 weight synthetic type F. Just the fluid change dropped stall speed by ~200 rpm, it doesn't feel appreciably different on the street. Worthy experiment for sure but don't expect much from the fluid change. It's my understanding the JD fluid is ~30 weight.
