I have both a full size and a Shield, but typically will be carrying the FS rather than the Shield. The Shield usually only gets carried in an NPE or when dressed up. Body shape makes a lot of difference in how and what you can carry and reasonably conceal. If you're in relatively good physical condition, it's pretty easy to conceal a full size pistol. If not, then it becomes way more difficult. Your clothing choices also factor in as to which pistol you can conceal.
When carrying the Shield, I always have two 8 round mags on my belt or in my pockets. That gives me roughly the same load out as a FS. I always carry at least one mag with the FS, for basically double the load out. Why? Because it's possible that I might need the extra bullets. The LEO in S.C. who shot the guy running away, took 8 or 9 shots to get him to the ground... running away from him. What if it was reversed and he had been running towards him? That's the reasoning behind carrying a FS over the Shield to begin with.
All my pistols are carried AIWB, because they tend to print less, the draw can be much more surreptitious and it is comfortable for me. Sometimes the FS prints a little, but you have to really be looking to catch it.
So, if it were me, I'd look at carrying your Pro...and leave the beside duties to the Shield.