Do they match?

they probably do tbh but if they don't

oh my...

won't see the match until next weekend to hold the habs hostage in not being able to sign anyone else

They'll match I guess. Montreal hopes that the Canes owner doesn't want to pay those 21M in 12 months, but without Aho this team will be really bad for the next couple of years which will have a negative impact on the revenues and profit. So if Dundon actually wants to make some kind of profit with the Canes, he has to spend money now on Aho

do you think they should have done it or just left it?

From hearing Bergevin’s press conference, this offer sheet really has nothing to do with hockey. Because from CAR perspective, specifically GM Wadell, this is the easiest decision ever. They have the cap space, and the compensation isn’t good enough. But MTL is making Dundon put his money where his mouth is. Pay up. Odds are that he will, but it’s interesting to see for sure!

I get it from Habs perspective. They had the offersheet option as backup plan in case they missed out on Duchene. Aho can carry a team and he had an impressive season.

But do I think it's a smart move? No. First, the AAV is not that high which makes it more likely the Canes will match it. I don't think it's smart to offer market value through an offersheet. If you go for it, really go for it. If you offered 5x9.5 or 9.75M you still don't have to give up 4 1st's and you've got a way bigger chance of getting him.
And teams don't like this. Habs have Poehlin and Kotkaniemi as RFA's in 2 years. Wouldn't be surprised if a team would offersheet one of them.

On the other hand, as long as the Canes don't match, Habs have over 8M that they can't use to overpay UFA's which might benefit them. And if the Habs get Aho, it would be a really good move with this compensation