(Been lurking for a while, finally joined to answer this)
I just got a new frame for my 320 with the Springer Magwell and Mag release. I've been using the base plates for a few months, more on those later.
Initial impressions on the magwell when I got it were positive. Once I used it for a couple reload drills I loved it. It adds nice weight and balance to the gun. Make the grip feel better in my hands and it's easy to find when inserting a mag. I opted to just buy a frame from them and it took a couple weeks to get it. The mag release helps and doesn't require as much of a "flip" when I'm reaching for it.
I've got the Apex trigger and Dawson sight set. No work to the action other than a few thousand rounds.
Now to the base plates. Personally I don't care for them. I like the look, the feel and added weight. I don't like that I can't add 5 rounds to 4 out of 6 of them even after extensive use. What I don't like ever more is the tiny hex set screw that holds it in place. I actually had to grind a small notch out of the mag to allow the screw to hold itself in place.
The screw is incrediblely small and easy to strip so taking the mags apart to clean is a nightmare. Last outdoor match I ran stripped on and discontinued use due to dirt in the carrier.
In hindsight I would have ordered just one instead of 6 at once. Thinkng of trying one of the Taylo Freelance but I don't think I'll tie anymore money into this as I've got a DVC Limited on ordered and that will be an entirely new set of expenses.