Didn’t play in the cup, but the only “problem” I had with it(when playing scrims/pugs) is that the merc pool feels too small to allow this sort of system at the moment. The choices you have are very limited, for example Sawbonez, imo, is just 100x better a medic than Aura is but there are no other medics than those two so with highlander rules someone gets forced into playing Aura which from what I’ve heard from most people feels really(REALLY) forced, regardless of if she is weak or not. Same applies to Arty.
Like I said before, it does make the balance more clear, before the ‘balance’ was Fraggers being strong because there were just always 2 or even 3 of him. Now Fragger isn’t nearly as ‘OP’ because he doesn’t stand out nearly as much anymore. Sawbonez and Skyhammer become much higher capability mercs compared to him because the fragging isn’t only on Fraggers shoulders anymore, which I think is a good thing.
I do think a lot of people would still like to see a ‘class based restriction’-system where you have free choice in what mercs you pick to fill roles. So you’d have 1 Soldier/Heavy(things like Fragger), 2 Fire Support, 3 Medics, 3 Engineers, 1 Covert at a time. I think for the size of the small mercpool right now this would feel a lot less restrictive. It means the killing potential is the same as in Highlander mode but it doesn’t force people into ‘the one merc that is left’ for some roles. F.E you could have 2 Skyhammers instead of 1 Skyhammer and forced 1 Arty and you could have 2 Sawbonez instead of 1 Sawbonez and forced 1 Aura. And inb4 people go ‘but Arty/Aura isn’t that weak if you use him/her right’, I agree they can be very effective. But this is about finding the middle ground between free choice of mercs and ‘forcing’ team composition. Also in the long run restricting with this class based system means that people have to stay within ‘restrictions’ even if there are more mercs similar to Fragger. When the game gets bigger with a much larger merc pool it would mean that there are maybe 6 Fire Support mercs, with Highlander that still means that f.e WhiteChapel can still be 4/5 Assault roles just wrecking the EV all the time or people running 3/4 ‘Fragger-esque’ mercs again because there are more high damage output mercs available. It will be slightly different as in that there are different mercs on the field, but the meta would likely turn into something very similar to what we had before Highlander. The way I(and I know plenty of other people) see it this system has less downsides than the other ones. Especially long term.
Ofcourse there is the ‘road between’, where you have Highlander+Class based restrictions. Where you have 1 merc per team rule and when the merc pool gets larger you restrict how many of a specific class mercs you can have. This is a decent middle ground I guess but it does mean that merc balance has to be spot on across the board for people not feeling like they are being forced into lesser mercs too much(there is always going to be a certain level of ‘forcing’ its unavoidable but if 1 merc in a role is clearly better somethings off we can all agree I think).
Edit: only problem with last said system is that it would have to be restricted from within the game to avoid people accidentally(or abusively) switching to other mercs, but then again that should also be the case for Highlander mode.