As said, it's like asking if you should get a new pickup or new car. It depends.
I'm not sure what you mean here:
"Are there any advantages to having a consealed with a 40 cal?"
Are you asking if there is any reason to own a concealable handgun when you have the 870, or are you asking if there is any advantage to .40 caliber?
If you are asking about caliber specifically, I am not a big .40 fan myself so admit some bias up front. As a compromise caliber, I don't see that it excels at anything except that-compromising. People who have studied gunshot wounds (like ballisticians, ER docs who are also gun enthusiasts, etc, and not gun magazine educated) generally feel that any of the top brand/line self defense ammo from 9mm through .45 is so close it hardly matters. Even Gunsite (the land of the .45) instructors will tell you they can't identify the caliber by watching gunfight footage or an autopsy. Those who want every edge they can, will go with the .45. Those who want more bullets go with 9mm. Most people I know who prefer the .40 choose it as a compromise.
The .40 fans will say it gives the best of both worlds- increased capacity over the .45 and increased power over the .45. I suppose, but as a pessimist, I look at the negative and see it giving the worst of both worlds also- reduced capacity compared to a 9mm and reduced power compared to the .45. I waffle back and forth between 9 and 45 sometimes, since I either want big bullets or lots of bullets. I've never been very happy sitting in the middle with several medium bullets. If I give up rounds in the magazine, I want big ones. If I give up bullet size, I want a bunch more of them.
I also think the .40 recoil is worse than either. It's not heavy, and no magnum in recoil but it feels sharp and quick to me. I'd rather have either the heavy push like the .45 or light and quick of the 9mm (both relatively speaking) than the fairly heavy/fairly quick of the .40. I'm not saying you or anyone else can't handle it, but if you've not even owned a handgun for eight years, I have doubts you will do your best shooting by jumping back in with a .40.
But if you're asking about the perceived necessity of having a concealable handgun (and I think that may be the case since you say you have the 870 and acted like that should cover about any defensive need):
This may sound harsh, but it is what it is- If one has to ask if there is any possible need for a concealed carry handgun, their mind isn't right for getting one yet.