You're right I was calculating the dps change wrong, but you're heavily overestimating the recharge needed for practical perma double stack. For meaningful perma you only would need it to recharge in ~65s, not ~60s. If you cast it at ~60s, you'll be casting rage INTO the crash, not out of it, wasting 10s of rage and the gaussian's proc. ~65 ensures it can be cast at the end of every crash. Also keep in mind that a crash doesn't put you at 0 damage, it floors you to 5%.
I launched the beta and took some actual damage values from abilities against 54 mobs to calculate a semi-accurate dps increase for the character, using 0 rage stacks as a baseline(100%). I did two tests. The first is with Agility/Melee Core, which is how I had the character built originally. That resulted in 134.14% dps with 1 stack, 154.58% average with 2 stacks for 20.44% average increase from double stacking.
To be fair to not stacking, I also tested with Musculature/Assault core for as much +damage% to get diminishing returns more heavily involved. With ageless and FF +rech proc I still had perma-double stack surprisingly, so no changes needed there. That test resulted in 128.85% average increase from one stack, and 140.27% average from two, for a 11.42% dps increase.
This does not take in to account aspects such as judgement incarnate ignoring damage modifiers, so that's a full strength nuke every other crash. Also I'm a bit lazy and don't really want to compare Assault core vs radial for this, but as radial scales off the initial hit, it will scale better with double stacking. This is also pure solo play again. I'd be curious to test with a kin, but again I'm lazy and that would take time. I think regardless, stacking at the very least has a valuable place in solo damage currently.
I realized from this that there is another reason that removing the stacking and just buffing SS numbers would be impractical. Rage buffs all damage (aside from abilities which ignore damage modifiers, of course). So any damaging abilities from a defensive set or from power/ancil/epic pools are buffed as well. The extra build up stack of double rage buffs those as well. It would take an immense amount of tweaking to find the sweet spot where the change wouldn't be a nerf to the kit. Even if that was found, it would still make attacks outside SS feel lackluster in comparison. Perhaps if that was the route people really wanted, rather than buffing just SS numbers, apply a passive damage modifier to rage on top of the activation. That way all powers would be buffed by the change and not just SS. I still think that sort of change would make rage feel a bit boring, though.