Oh, and just because no-one has spotted it, a century break requires a powerplay. Without one, the maximum break would be 99 (9x1 + 1x2 + 1x3 + 1x4 + 1x5 + 1x6 + 10x7). That means they're probably going to be somewhat rare.
Yeah but a powerplay just means that the middle red has been potted, which is fairly likely in big breaks (the exception being cases where it gets plucked off randomly without a break ensuing obviously). From that point on, every pot for the next 2 minutes counts double, and given the 20-second rule, that will include a minimum of at least 6 shots (so in the case of a continuous break, an extremely good chance of at least 4 colours being potted).
Now, obviously century breaks may well still be rarish, but it really all depends on what happens with that middle red. A fast player like ROS or Drago, if they get into position early in the game with a chance to really exploit the PP, could easily rack up a 100 break bearing in mind that say 6 blacks followed by 5 reds (11 balls in 120s) would give you 95pts on its own. Even if you don't chain a break onto the PP red, as mentioned above, we've got 6+ shots so unless there's a safety exchange there's a fair chance of at least a few bonus points should either player be able to start a break.
I think this will add a little bit of an extra tactical element to the game, in that you will be reluctant to pot the middle red unless you are fairly sure you can either get on a colour. Because if you have to end your break, you will be handing the table to your opponent with the PP still active. Also, it will change the game a little in terms of how many points you are leaving on the table, theoretically if a player was to do a total clearance within 2 mins of potting the middle red, they would get a 197 break. Very unlikely but the point is that the old days of simply worrying about how many points are the on table are warped a bit, you need to think more along the lines of
realistically how many points can they get..... should I try to pot the PP red myself, and then timewaste for 20s etc. Probably not actually if we're dealing in points rather than frames!
Another (unrelated) thing to consider is that with 9 reds instead of 15 there will arguably be more chance of snookers I guess i.e. earlier in the game there will be fewer open reds than normal (although again the pool-style breakoff rule means that you'd expect less clustering... hard one to call until we see it in action).
In summation I'm actually quite keen to see this played and get a feel for how it works, whether players can mentally adjust to purely playing for points rather than worrying about the situation in that frame etc.