Quick tip, the orange room in quarry has a plunger you can press to the right of the door that gives you a ton of xp and allows you to get your second perk way earlier and the reason engi is called the strongest class is because summon weapon builds are absolutely busted.
Like Yomkool said, the issue would be finding people who want to run that category. I know a lot of the existing runners wouldn't be into it because it would basically just be the old any% run from before glitches were allowed, which ends up being longer than normal runs and Iris takes up like a third of the run. Many have said in the past that they don't want to do it because of that.
You could propose the idea on the discord and see if people are interested or you might be able to convince some new people to start running if they think the category would be interesting.
Another issue I have with merging versions is that should the main two strats get bug fixed/nerfed (because summons engi is only as strong as it is due to a bugged interaction and a lot of people I've talked to who play at the top level dislike how busted first ranger is and want first removed) it means that it would be incredibly difficult to beat those times from older patches that would be taking the top spots on the leaderboard. I would argue that would feel far worse than the current system.
The powercreep between updates is very strong and typically every new update leads to a faster world record once runners get around to working for it. Not really a need to have the versions unified, especially as it creates some incentive to run more each patch because of runs getting cemented whenever an update releases.
Merging the class categories has also seemingly led to most classes dying as now there's less incentive to run them over the classes that actually have a chance at world records. Granted I know there's a lot more factors involved in other classes getting run less besides that so that might be an unfair connection to make.
The Super Update added Harmony Square as a path branching off of Haven. This path has no xp requirement, so you can gun straight for the goliaths and then go through Harmony instead of District.
This saves a good chunk of time, so I recommend anyone running use that instead of the district route. It's more difficult, but it's worth it.
Have fun rocket jumping.