Yep; unless you need SAS support I would recommend onboard SATA first.
OP, I have the same HBA card as you, it gets toasty even just idling, and even hotter once you throw a load onto it. I measured ~10W power use just idling (no drives attached to HBA). I almost guarantee using onboard SATA will be more power efficient.
Even better, is if you can physically remove the HBA card until you need it.
About 275 Canadian Pesos for those keeping track. Wish we had the prices you guys south of the border seem to get!
In the past I've given up buying locally and instead bulk ordered drives in the US and shipping to a US address, then package-forwarding them over the border. Saved quite a lot, duties on HDDs aren't that high!