I would still suggest just getting the tree, yes. The initial 0UB 6* weapon just does not seem that useful to me. Especially when you could alternatively make a Chimera T2 and get pretty close to it, and neither is going to get you into eVolk anyway. Unless you make a staff, in which case it looks like the Chimera actually wins out HP-wise so would still be better.
And on that note... so, obviously, I went and got HLowen his 0UB HD2 to use for eVolk (and theoretically mHMS). And I don't really regret it, as I have easily gotten into rooms as a result. To the point that I uhhhhh kinda farmed a MUB 6* for Xania already. But if you have HLowen+PSiren and can manage with a Chimera T2, honestly it may be worth trying to break into eVolk with that instead? And that's regardless of who you want to actually use for it long term.
Cause I think you could still get past might gates an acceptable amount of the time with just the T2; hosting may also work fine, though I guess people may be arbitrarily annoyed at you vs just accepting it when you're the last one joining their room, and so on? And you risk not being able to lock out overly weak players, I guess. As is with my HD2 I'm joining with an 8.4k fake loadout with just the highest possible might prints/dragon, then switching to my real 7.8k loadout, but some people do set rooms low enough that you could still get into them with a T2 with the right facilities + fake loadout. As far as making the 6* weapon, Expert's first clear bonus + weeklies + a couple more runs got me to 1UB already, and since you got 3-5 gold fragments per run, it's only 6-10 runs per unbind even without weeklies. And I'm not sure if the gold fragments in weeklies vary, but I got 6 for all mine this week, which means 9 per run at worst for those first 3 runs. So worst case you can just get Expert weeklies for maybe a month, with those 3 or 4 runs a week getting an unbind (so if you don't fame beyond this you won't even have to worry as much about getting into rooms), and then have a MUB 6* to actually use on someone else going forward. Just feels like it's reasonably worth taking a shot at if you have HLowen + PSiren to begin with and may not have a fire HD2 ready anytime soon.
...so that would be smarter than going the HD2 route like me, but it was probably actually worth the easier time with rooms as I'm apparenly a fool who suddenly wanted to spend even more time farming, I guess? Like the issue is more that if there's Master revives, it still would have been worth doing this pace 2 weeks later to save the time on getting the HD2 at all. But. Still.
...well, there's also that I had no real need to get the 6* so quickly either, but it is very nice to jump up in power so fast! Even just casually running more is gonna be buffing up my fire team quickly, while my day to day co-op focus goes back to a more varied set of high dragons that I'll be actively running, seeing as I've now essentially "finished" both cycles for the first time. I gotta get back into doing Jupiter and actually remember what HZD is like, for example... I want to build up some more HD1s, get my Fafnirs up more, and there's of course mentoring to do both for the bonus and in the sense of teaching alliance members who now want to try running more fights...