My guess is its less an issue of safety than of how you want it to taste.
Nitrates have been linked to GI cancer as they develop into nitrosamines. Obviously it's a dose dependant issue, like smoking. Additionally, smoked foods have high concentrations of another carcinogen-Polycyclic aromatic hydrocarbons (PAHs). Interestingly enough it seems that a (dark) beer marinade can reduce the levels of PAHs in grilled food (though smoking generates PAHs through another method) :http://pubs.acs.org/doi/abs/10.1021/jf404966w. It should be noted that a 2012 study abstract I found indicated the reaction between the aluminum pan and the meat lessened the levels of PAHs. The short of it is that there is some benefit to considering intake of smoked red meats, especially when preserved with nitrates. (sorry neurotic med student here).
That being said I love chefsteps pastrami ribs recipe and did not skimp on the prague salt. I attempt to use it only sparingly in my diet.
surprised it took me so long to find this thread. Tbh its nice to have a nice crowd away from the fb scene. When i get a chance i love to mess with my masterbuilt electric+amazn pellet smoker+anova.