Very cool that you started prudent...
3.5 check
7.5 check
Very good!!
So usually I inform people after the trainer kite... they may want to look less at the kite size and more at local conditions and personal skill
level. This has to assume that you are able to step into the truth of your ability. As 80% of people tend to inaccurately estimate their ability be
it over or under estimate. A very dramatic gap either way.
You've indicated the need for a kite in light winds (5-10) so really assuming your local riding conditions and skill level with de power foils is up
there in skill level.... 12m foils in my mind start the light wind kite category and kite sizes go well in to the 20 m + size range.
A nessesary step for light wind kite selections may include the self assessment of good flying, launching, landing both alone and assisted, safety
system mastery (lots of practice) as these can all help you get an idea of what you think your ready for.
It could be time for the 12+ m foil or 13-15 m leading edge inflatable.
However your skill level with a larger kite is paramount to the success and safety as well as sustainable integrity with regards to the kite and you,
in other words you don't break the kite or yourself.
12-15 m open cell foils are awesome and amazing products but also can very dangerous.... Even in the light winds..
That said tour presented choices, the Montana 12.5 is great! But you may find the 10 m Apex a little under powered.
But concider whether you ride/fly typically under powered or over powered?
Are you really fatigued after a tug of war with the kites per session or are you trembling from excitement and energy still in reserve for kiting
later, when your done for the day, ready for more?
If you tend to find yourself riding/flying under powered a 12- 15 m kite in light winds might surprise you in it's strength of pulling power compared
to the wind speed.
Whatever you do, treat each kite (size changes included) differently, treat each launch as a new one, be alert and start slow.... In light winds
ideally....and get a feel for whatever kite you choose to purchase! Learn the new kite in winds that are almost not there....and master everything
you can ... This mastery means there are likely no surprises you'll find in the kites reactions to wind, steering, quick releasing behavior, etc...
You'll know the kite like you know your favorite way if making tea....you'll be prepared for days when the wind changes and increases dramatically....
Which it will!
It's an exciting time! Filled with adventures!
Have fun and be safe!
Good luck!
And feel free to keep asking questions .....