Hmmm... Well I mean it really depends on what you value honestly, I wouldn't say that one is strictly better than the other. Awoken Parvati and Awoken Lakshmi definitely have great new damage multipliers, but their RCV multipliers are FAR inferior to the Awoken Norse series (1.5x RCV versus 2.5x RCV).
I mean you can say it's a trade off between RCV and ATK, but honestly I would prefer to have more RCV on a tank leader. Recovering your gigantic HP back to full might be pretty hard to pull off with only a 1.5x RCV multiplier, but it'd be a ton easier with 2.5x. By opting for only a 1.5x RCV multiplier over a 2.5x RCV multiplier, your team becomes incredibly less tanky and it becomes pretty hard to recover back your gigantic HP in a single turn.
I mean having better attack is great and all, but I don't think the Awoken Norse / Dragonbound combos really struggle too much with damage. They're more than capable of taking down Kali and pretty much everything else in Arena with their current damage multiplier (not as good as say the MP dragons obviously). If you're concerned with dealing incredible damage, I would honestly just stick with double Parvati or double Lahkshmi. I don't think they're 1.5x RCV multiplier makes them good enough to be tank leaders.
Another thing I'd like to point out is that Paravati and Lakshmi have pretty mediocre actives. I mean they're decent because they help activate their own leaderskill, but they're mediocre at best on their team. With a dragonbound / norse team, you can be assured that pretty much every single sub on your team is going to have an excellent active that are great.
Of course the BIGGEST downsides are the limit in sub choices now and the extra orb matching style, as you point out. I feel like this issue is a lot bigger than you make it out to be because this bars you from using amazing subs such as: Artemis, GValk, Awoken Meimie, Hermes, BValk, and Awoken Karin. Artemis and Hermes are most notable on the list because they're probably your best burst options on a green or blue row-based team and now you don't have any access to them. BValk and GValk are lesser casualties, but they're still casualties nontheless because they have such an incredibly quick active that can fix the dragonbound boards along with solid awakenings. Awoken Meimei is a questionable loss because she doesn't have any rows but she combos amazingly with Michael, but Awoken Karin is definitely a major loss for blue rows. Not only that, you're going to have to prioritize heart makers a lot more so you won't be able to freely use other subs. This will probably lead you into subbing in Verdandi or Skuld instead of other subs which further limits your options.
The extra time needed for orb matching will probably increase the margin of error a lot for the team because these teams probably won't have many time extends at all. It also doesn't help at all that they have lower RCV multipliers so it's not like they can easily come back after a taking a hit either.
TLDR: I disagree LOL-- Dragonbound / Norse combos have a larger subpool and are a lot more resilient than Parvati / Freyja and Lakshmi / Ryune. If you're concerned with damage, I would rather just do Parvati x2 or Lakshmi x2