Both Belton Brick reverb pedals so they have the same kind of sound, an almost slapback-like decay, (which some people aren't keen on) and have a touch of pre-delay, which is ideal for using heavy amounts of overdrive or fuzz.
Mr. Springgy decay is alot longer than the Super, almost like there is another subtle second decay circuit is kicking in over the top of the first. Has a nice atmospheric, ambient tone to it as a result. Has a really great buffer in it. Small footprint!
Super Surf is less atmospheric due to a shorter decay, even maxed out. Tone control is pretty good. Nails the Mr. Springgy at about noon. Less/darker is fairly useless, but the added treble is bright without being harsh. Level control is useful, rspecially since there's an internal trimpot to increase the volume of the first reverb so you can make that louder, then just dial the level back with the control.
Mr. Springgy has quite an "80's rack reverb" tone to it, which may not be for some. Very lush yet subtle. Super Surf's Res(decay) and Depth controls don't have a huge range to them. The new, second reverb may be pointless for most. It's like a second, purely wet reverb put on top afew milliseconds after the first.
Overall, I'd suggest the Mr.Springgy if you play way more clean and slow. Maybe go for the Super if you're after a more 'physical' spring tank kind of sound and/or louder/extreme reverb.
I think that's it. I wish the Super had the longer decay of the Mr.Springgy, then it'd be perfect, but now it's a hard choice which one to keep!
Got the Mr.Springgy from Lee Jackson's ebay store, and the Super Surf Rider from ProGuitarShop.