So, is there really any good reason for me to hold on to this Sig, because I am considering selling it?
I am not a collector, every gun I own serves a specific purpose from woods carry, concealed carry, to home defense. I don't like to keep guns that I don't use as I just see it as a waste, I also don't feel the need to own two different guns that serve the exact same purpose as one will just sit in the safe never seeing the light of day. If you are trying to build up a collection then keep it, but if you can sell it and put the money towards something you actually need and will use, then go for it.
Also since you prefer the Glock, it would make no sense to designate the Glock for carry and the Sig for home defense duty since they differ vastly. Main reason being the Glock has a much lower bore axis, if you are used to shooting Glocks, picking up the Sig to use in a pinch might throw you off since they differ so much. Not to mention the triggers and manual of arms for both are completely different. Stick with what you like and what works for you.