The rise in pH will naturally slow down at higher pH as well as at lower TA. This chart can give you a rough idea of how over-carbonated your pool water is with respect to air so you can see that at 8.0 and reasonably low TA the pool is not very over-carbonated.

Anyway, the main problem with higher pH is if your CH and TA are also high enough to cause calcium scaling. This is most problematic with your salt cell since scale will often form there first. At least with the borates, this problem is lessened. The other issue for high pH is the possibility of metal staining. So, as Ben's high pH pool page indicates, it is certainly doable but you have to understand the risks. You can certainly manage the TA and possibly the CH to have the saturation index still be near 0 even at high pH so that just leaves the problem of metal staining which may not be of concern if you don't have metal ions in your water.

The borates only slightly affect the saturation index and if you use The Pool Calculator then that is handled for you automatically.