You can save seeds McP if they are open pollinated. The Phoenix tomato is a hybrid and will not come true from seed to the parent plant. You may also get cross pollination with OP varieties and they may not come true either, but the chance is fairly low in my experience even if they are planted in close proximity. I usually try and save seeds from the earliest, best tomatoes to minimize the chance they crossed as well. You can also bag blooms to save seed from as tomatoes are self pollinating. Saving seeds is fun and yes, after a generation or two they will be acclimated to our growing conditions...
