If I have not done so before, welcome to the T&TH forum. It's a good, friendly place with helpful folks who'll gladly share information with you.
I own both of those guns and shoot both of them on a pretty regular basis.
I installed 2 of the ShurShot stocks on 2 of my guns and like them. They are lighter than the synthetic stocks that were on my guns. They have a somewhat shorter LOP but a Shooter's Friend Recoil Pad fits perfectly over the new SuperCell recoil pad and adds the .25" that I need.
You can really pull that stock into your shoulder pocket and hold it much steadier than the traditional stock. I prefer it to any thumbhole stock I've tried because there's no slamming my thumb in those too small holes of the thumbhole stocks. I do believe the SuperCell pad is better than the pad it replaced but I still like the SF over it, just as I do with every gun I shoot.
I bought the first Nova and still have it. The difference of course in the Super Nova and the Nova is that the stock can be removed from the receiver of the SN. Now with the Comfortech stock, it shares some similarity to the SBE in that respect. That stock helped the SBEII and also helps the Super Nova. It still kicks however and I use the SF on it as well.
It takes a bit more time to break-in the SN than the 870, in my experience. It also has the 3.5" chamber standard, like the Super Magnum 870, if that's an advantage to you.
I like the SN for a waterfowl gun or even an upland gun but prefer the 870 for turkey hunting. The main reason for that it pretty simple. Once your SN is broken-in, the forend wants to slide backward from the recoil of your shot. That's a good thing perhaps for wing shooting but it's not too good for the type of shooting we do at turkeys. It can easily cause a miss.
I've watched shooters fire a Nova/Super Nova at still target shoots and have seen this happen quite often. The muzzle will rise at just the wrong time and cause a high shot. To counter this, you must put forward pressure on the forend and that's just not conducive to good shooting, at least in my experience.
My vote is for the 870 for that reason and also due to the many other "add-on" products made for the 870.
I hope that helps some.
"If he's out of range, it just means that he has another day and so do you."