Should I start to spend my ISO for new PVP matchmaking?

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Hi. First of all, here is my roster:

http://mpq.gamependium.com/rosters/dp

Tl:DR - I'm in a middle of transition to 3*, having 120-130 lvl championed 2*, 10 or so 3* heroes with full covers (some not optimal) and basically all other 3* with various amount of covers.

Since then I leveled up my 3* evenly and kept them just under the lovest 2* champion (now it's Daken lvl 117, so almost all my 3* capped on 116 lvl). And since then I didn't have any problem with that. In PvP I could easily find opponents with 100-150 lvl heroes. In PvE easy nods contained 70 lvl heroes, normal - 110, hard 160 or something like that. But new PvP matchmaking kicked in, so I desperately need your advice. New PvP is vased not only on character's levels (which is pretty low in my case) but on power levels (and I have low leveled fully covered 3*).
Basically, I expect that my PvP experience will get a lot harder because of this.

So I have two options. I keep leveling my heroes evenly as I planned before and deal with increased difficulty like a man. Or I spend my 700 000 ISO on leveling ~7 fully covered 3* heroes (or some of not fully covered maybe) and start playing only them.

So what do you think, which way is better, and if you think that I should start spending ISO, which heroes should I choose?

Thanks for all the answers.