Hey sorry I didn't see your question sooner.
I'm really liking the JDJ. It is definitely a handfull to shoot, no doubts there. I still say it's easier to shoot than my 45-70 if I'm running full power smokeless loads in it. The JDJ barrel is 16", from SSK, and has a radial brake on it. The recoil on that one is literally straight back, no muzzle rise at all. The 45-70 barrel is a 14" factory barrel with the "muzzle tamer" on it, so not quite a full radial brake. The recoil on the 45-70 barrel with full power smokeless loads creates quite a bit of muzzle flip, but also the gun torques sideways in your hand at the same time.
Of the two, the JDJ is easier to shoot for extended periods than the 45-70.
Now for just pure entertainment, the 45-70 barrel, with real blackpowder loads is a whole bunch of fun to shoot. The recoil with those loads is extremely manageable, and I shoot it quite easily one-handed. That is pretty much all I shoot out of the 45-70 bbl now, is BP loads. It makes a huge hit at the public range I frequent.
For the JDJ, my favorite load is with the Hornady 270 SP Interlock bullet, and 48.5 grs of IMR 4064. This load is below "max" according to the data sheet from SSK.
I have let several of the range regulars shoot the JDJ, but I would not let a beginner shooter try it. I'll let just about anyone who wants to shoot the BP loads from my 45-70 bbl.
If you were near Phx, AZ or planning to come through, I'm usually at Ben Avery shooting range every Sunday morning. I'd let you have a try at it.