Adding a ninth map to invite brings up something that's bugged me about pick/bans in TF2 for these past few seasons: Why do we do alternating pick/bans for playoffs with an 8 map pool?
Right now, with our 8 map pool, this is how we're doing things:
A Bans | B Bans | A Picks Map 1 | B Picks Map 2 | A Bans | B Bans | A Picks Map 3
The way it is right now, the higher seeded team gets both advantages in the draft: they get to choose how to kick off the series, and where the series will end. This just strikes me as strange coming from CS, where there's a 7 map pool, so for playoffs deciders there's actually a choice to be made on whether you want to go for the throat, or take the safety pick and make sure you can take map 3 if it goes that far. That means there's an actual decision to be made for whether you want to be A or B. But in TF2 with the draft the way it is and an 8 map pool, your choices are to make both of the most important decisions for the draft, or make neither.
And the solution is really easy: Just have B do both of the final bans, so that it looks like this:
A Bans | B Bans | A Picks Map 1 | B Picks Map 2 | A Bans | B Bans | B Picks Map 3
I guess the question comes down to how much value you should get out of a higher seed. Seeding in TF2 is more valuable than in other games with similar playoffs structures (CS is the only game I have experience with this in, but my understanding is that MOBAs and fighting games use a similar system for hero / stage drafts). It just strikes me as strange and possibly an oversight, since when I looked back at my RGL S1 playoffs pages, (and I just checked my ESEA playoffs pages, they also had the same issue) the instructions had the teams banning 6 of the 8 maps. If we've decided that the seeding should be worth more, that's one thing, but if the system is the way it is just because nobody's ever thought about it, I think that this is something worth talking about.
Or you could just add one more map (or take away one) and not have to worry about it.