I suspect (speaking from my vantage point over here at latitude 34) that you'll find any of the good wool fabrics to breathe better than the Marton Mills PV.

I get plenty of mileage from my USAK semi-trads, but I also wear an 8 yard 13-ounce kilt year round. With either fabric, the only area that ever gets hot is the waist. The rest has built-in ventilation.

You will hear the experts recommend heavier wool for lower-yardage kilts, especially in the 4 yard box pleat variety.

If you're determined to get 13-ounce (which is still very nice fabric), consider a 5 yard knife pleat like the extremely popular USAK 5 yard.

Disclaimer: I grew up in this area, where humidity ranges from nice to unspeakable---it was 85F yesterday. I do not fear The Wool. Wool garments breathe, and they wick the moisture like no one's business. Ounce for ounce, wool is cooler than cotton, PV, or almost anything except lightweight linen. Your personal thermostat may differ, but I say: Embrace the wool.

Oh yeah, also I'm a little opinionated.