You will get loads of opposite responses on this one, just so you know Dave, you might not be able to get "wiser".
The supershort masts are IMO nonsense, and a reminiscence from the sup/surf foils where they are needed for paddling up on shallow reef/sandbanks.
This is not an issue when kitesurfing, as with longer masts you still dont have more mast under the water.
I got three, 83 / 91.5 /100 cm masts.
Use the 91.5 mostly, as when light wind and not much chop or swell it works great overall if I should just have one mast also, the "go to" mast.
Whenever it is "good" waves, and/or more wind and chop or sideshore, I choose the 100 cm.
In fact yesterday when used with a 3.5 m2 kite, it got me thinking how often I use the 91.5 where the 100 would be the better choice and SO much better, no doubt.
Lazy, if the 91.5 was on the flyer that very day, I might just grab it.
The 83 cm is a different animal. Use it for marginal dead onshore winds only, 5-7 knots.
If the wind picks up, this short length is pure rubbish IMO, and worth nothing (but getting better, as a LOT harder to ride).
I know others will have maybe the complete opposite opinion
And no, you wont gain with an 111 cm in my experience.
If you dont have a big "urge" for a longer mast, keep the 91 cm, spot on overall for your Onda 633