Welcome to THR, Law Enforcement! Good to meet you.
Whoa, I'd never consider myself an expert on recommending what you, or anyone else MUST do. I make observations about what works for me, and try to explain why. For instance:
* If the controls of any handgun are predominantly on the left side, do you have to break your grip to operate them? Consistent grip position is very important to accurate, controlled shooting. Operating the decockers on my Sig P229 and P239 requires me to break my grip completely, but, if I'm in a state of shooting where I am decocking, does that matter? It sure is nice to have that flat, smooth right side on the P239 against my side when I'm wearing it IWB, and in fact, the P239 is my most common IWB carry handgun.
* Does the model of firearm I'm shooting normally have ambidextrous controls? If not, should my own specific firearm be different? I'd like to have a left-hand AR, but then I'd train with a rifle that is different than most. Would that be detrimental in an emergency situation where I had to use a "normal" AR (or any other firearm)? Same thing with just having an ambi safety on the AR. It works a lot easier using the left thumb on the right side of the rifle, but I can use the standard safety well, and most ARs don't have them. I have more than one (heh) AR, and not all of them have an ambi safety. Gets confusing once in awhile... But, if you only intend to shoot your own firearm, build or buy what works best for you and train with it.
Now, there are exceptions to that thought process. Most Browning High Powers you run into today have ambi safeties. I have a less recent BHP (early 70's) that only has the right hand safety. I have considered converting that one over to an ambi, but then again, ALL BHP have a right hand safety (even the ambi's) -- I may as well learn how to use it. (Unfortunately, I tend not to carry that handgun, because of the safety. It is such a nice gun, though!) 1911's are getting that way. Anything but the entry level models usually have an ambi safety. So, consider, as you have mentioned, the next point.
* Is it really worth the cost and reliability issues? Converting all my ARs over might cost the same amount as a mess of ammo or a new railed forearm. Hmm... Sure, they can be installed professionally and work very well, but does it introduce something else that might either make the firearm less reliable or subject to breakage? (Probably not, but it does happen.)
I've learned to say, "Thank you, I'll certainly take that into consideration." Then, consider and evaluate the advice, and do what works for you.