Q1 - Are there other good options in this price-range?
Q2 – Will the Sector be usable the way I want or should I bite the bullet and push thru the higher learning curve on the Cabrinha?
In the price range I'd say perhaps a used race board if you can find one. I'd say your pick is pretty much dead on.
I've not yet tried Cab, but there are several of them around and watching them, my gut feel is that you'll see improved upwind performance compared to Sector 60 V2.
Having said that, your skills will determine your performance for a quite a while:
In this video
you can see a very good kiter (green cabrinha) on Sector V2 go faster and better upwind than the rest of the fleet - a mixture of Sectors, newest race boards and at least one Cab. I'm able to cross his bow only because he had to duck to avoid another kiter on North 69LTD.
In this one
he clearly outsails a kiter on Augera CR69HW (yellow kite), faster and better angle.
My take on this is that if you gonna ride on rougher/choppier water, benefits of Cab's better lift may not show if you can ride Sector easier/better. Very flat water will benefit better performing board.
Racing against cats will be hard due to worse upwind performance of Sector. At least that what I have seen sailing side by side Nacra cats on very flat water. Again in the chop it might be different.
If racing and learning quirks of racing boards is the prime consideration and you don't care to use the board in small surf, than I'd be tempted to get Cab. Otherwise Sector is simply soooo much more versatile that it is an obvious choice.