Keep the mini and get an SS. This is MCB after all so the more the merrier!
Seriously though, even though IMHO the mini is a great little gun, in a year from now it will be "old" for an electro. Anything from PPS will hold it's value for a long time to come. I'd sell the mini while it still has a decent price on it and go for the SS. If you ever regret it, in a year or so you can probably buy another mini for $100-$150.