First off: everything @Flox said.
And with regard to:
I’m fairly familiar, along with @Flox, of Rockstor’s development and your are correct that our installer focus has been completely biased towards the openSUSE front and I hope to have an announcement for the forum on this front soon, just got to clear some legal use stuff with the openSUSE folks first. But given the efforts you have both gone too to try and make the old installer work on the new shiny you both have, maybe it would be less work all around for you to strongly consider jumping on the “alpha testing” openSUSE variant, which for the time being at least starts out with a vanilla openSUSE Leap 15.1 install with a few minor configuration changes from default and then a manual rpm install from our openSUSE testing repository. The following “Announcements” forum post from a month ago details what to expect from it and us:
That would at least mean you are reaching into the future for a solution rather than the past. 
Note however that we don’t yet have a stable rpm offering for Leap15.1 yet as given the existing wrinkles it doesn’t yet seem fitting. But your experiments and informed reports of your findings can only help with moving us closer to that situation which would of course be best all around. So yes, early days, but worth a try if you are fairly technical, ‘linux’ aware, and fairly game. Just make sure to read fully all the links from the referenced forum post.
@def_monk Just noticed your edit:
So yes in short, hopefully.
The exact same code in GitHub is used, concurrently, to build our CentOS stable rpm as is used to build our openSUSE Leap15.1 rpms. We just have some kinks to work out where stuff works in CentOS but not in openSUSE. Such as those posts indicate, ie the terminal app within the Web-UI and creating shares on the system drive. Scrub progress reporting is likely broken also but the scrub should still be instigated and should also complete as intended, just the reporting of progress as the command output format changed in one of the btrfs kernel back-ports. So in short the rpms are all rolled from the same GitHub tag.
From this I do think you should give it a try. Just keep in mind that we are ‘in progress’ and are still very much supporting the CentOS variant until the openSUSE offering is ‘on par’ at least. But your informed and active (if patient) involvement can only help here. Plus you’d be running a much much newer btrfs stack as openSUSE back-port a tone of btrfs stuff to their seemingly similarly aged kernel.
See @Flox recent post on this:
I’m working on the project, and with your above caveats, and you having read the various warnings and your obviously ‘game’ attitude then why not. We are building this project in the open via community collaboration so I’m all for folks trying out the openSUSE offering. But as you intimate, nobody wants the early nature of these openSUSE offering to spoil the work we have all put into the project thus far on the CenOS side. But if you understand that it’s not yet at feature parity and are game to chip in to make it so then great. Especially given your rather limited options with regard to our now ageing CentOS installer. We have had a few folks here on the forum running source builds already on openSUSE but that’s really very much only sutable for those developing rockstor. And given the testing rpms are now available that should make for a better testing platform for us moving this whole openSUSE thing along so we can offer a stable variant. Which is the entire point of the testing offering in the first place of course.
So along with my own fairly game attitude on this (with noted caveats) I’d also take into account anything @Flox has to say on the matter rather seriously as he has done a lot of the openSUSE testing to date.
Given Rockstor support is predominantly community based the more folks trying the openSUSE testing branch the better. Just heed the warnings and know that core rockstor developers can only really spend time on informed reports as 20 reports of a documented known issue is frustrating at best.
Hope it work out and keep us updated on your progress. I’ll link here to my “Built on openSUSE” installer announcement once I’ve gotten all the ducks in a row, but there are quite a few ducks.
Hope that helps.