any feedback on calcium levels and if there's any negative effects at higher levels?
In ale brewing, there doesn't seem to be too much detriment to brewing with high calcium content. One aspect that may be either good or bad, is that yeast flocculate and settle much faster with high calcium content. For example, Burton beers were always praised for their clarity. But a negative would be if your ale yeast flocs too quickly and your beer doesn't attenuate and you have to somehow rouse the yeast to get it to finish its job!
In lager brewing, there definitely is a negative to high calcium. It can interfere with the yeast metabolism and can cause premature flocculation (as above).
In general, calcium doesn't really affect flavor. Its the other ions (Cl, SO4, HCO3) that affect flavor. 50 ppm Ca seems to be a minimum value for ales since you may have problems getting the beer to clear quickly at levels lower than that. Lagers don't have to clear quickly since they are 'lagered' and that slow process does the work. Of course, this whole clearing issue is easy to fix...either fine, filter, or centrifuge the beer to remove the yeast.
AHA members will get to read more about this calcium in brewing water in the March/April 2015 issue of Zymurgy. It helps put to rest the myth that brewing water should always have at least 50 ppm calcium.