I think it's a good starting point, and if you feel the want/need to go to a more advanced mix, it won't be difficult to upgrade, because you'll have a better idea of what you need with your PJ, in your conditions.
It sounds to me like you won't have too much Ambient Light, so it will get you started.
I had a white screen(Flat white ceiling paint), and it did fine when dark, but it began washing out quickly when I put lights on, so I painted a gray screen(with 2 topcoats of #780 Poly), and the results are MUCH improved when lights are on.
It all depends on how much effort you want to put into the initial screen, if you want or need the BEST AL performing screen right away, I would suggest you look at some of the more advanced mixes.
If PJC is anywhere near correct, you'll be around 16fl at that size screen, which is according to them " Recommended brightness for dark Rooms", I think it's PLENTY bright myself, according to them I'm at like 12fl, and mine is plenty bright to me.
Thats IMO, others may have different views on the matter.
Why waste $ on more cheap stuff, it's like challenging a dragon with a pocket knife.