If you have a light rig, especially on a TJ, you're not going to see much difference. The Black Max shocks we're softest riding shock I could find and they are still to stiff for my liking. Having been through several after market shocks, there's no doubt in my mind that shocks make the ride. However, there comes a point where off-the-shelf shocks won't do the trick and you need ones that are custom tuned. In order to get the ride I want, I'm at that point with my TJ.
In contrast, I'm also running BM shocks on my LJ and the ride is night and day difference compared to gas charged shocks. Part of this is weight, but part is also the higher spring rate of the H&R springs on my TJ (The LJ runs ProComp 55298 and 55297 springs). After contacting H&R a couple times, I was told they will not tell you anything about spring numbers. Not even free length. The only thing H&R will tell you is that the springs are Progressive. If you look at them compared to stock, the heights are basically the same. In fact, the stock front springs are taller than the H&R springs.
Bottom line, all rigs would benefit from custom tuned shocks. If you're trying to build a lighter Jeep, this will become apparent quickly!
Front = .565" thick & 16 3/8" tall
Rear = .605" thick & 12 5/8" tall
Based on what I could find, here's how the free lengths compare:
Stock Front = 17"
H&R Front = 16 3/8"
Stock Rear = 11 3/4"
H&R Rear = 12 5/8"