It's hardiness is similar to lemon and might be a challenge to do well in 8b, but possible. The seeds are quite large and I've not heard of anyone eating them on purpose or by mistake but also don't know that they're very toxic either. It's not a fruit that's been studied much. I've eaten quite a few fruits at one time, some with skins, and never felt sleepy from eating them. I'm aware of such information but think it's over-stated. I usually peel the fruits but not always, especially when eating out in the field such as the expedition a group of us made last year to Bob Chamber's groves in northern San Diego County. See my the photos, etc. I've posted at
WhiteSapote.com