A lot of unknowns and a lot to like about Izzy v TK head to head.
But what of the backrow battle? Dempsey, Hooper, Holloway v Fardy, Butler, Smiler will have possibly a bigger bearing on the outcome imo. Hooper's attacking game is a huge threat and will need to be contained by the Brumbies, while Holloway is showing that he's capable of busting the line also at this level.
It also seems to me that despite the Tahs' lineout being quite maligned game after game, they actually got the better of the Brumbies lineout in their earlier clash. Though with 4 quality jumpers in this team, I expect the Brumbies will probably finish in front at the set piece contest.
After winning the set piece clashes, the Brumbies need to do more and be more accurate in their backline attack. They were on fire against the Hurricanes but despite showing some promising signs in later games, they haven't been able to dominate other defenses seemingly because of an inability to finish off their attack. Lack of outright pace might be a constraint. And please be very selective about where and when to use the box kick - from around your own 22m line is mostly not a good idea.
If they get away with this one, the Brumbies should be able to go on to win the conference, but a loss will keep it very much an open contest with the Rebels and Tahs.