I would suggest just taking the plunge and getting one - it will find a place in your setup.
I do a bit of Max as do others on this list so yes some 'custom' stuff will end up coming out.
It is a 'Max app' there kinda is no 'full API' that would allow others to write in other languages apart from Max
Currently the pedal does most of what other pedals do, quite a bit that no other pedal can do and more . . .
The 'resource' issue is not as great as it used to be ( nor as much of an issue as many make out imho)
With the last Mac update it is down to about 650M - it should not be an issue running Live, SoftStep and other apps on a MacBook with 4G of ram and I believe any one doing music should have at least that in their notebooks. It is also important to have a separate user setup for music-making only that maximises ram availability. Lots of additional system features off or manually controlled etc. . . And no internetting whilst doing music etc. . . .
I use the SS with a Roland Vg 99, and FC300 footpedal, a KMI StringPort and it's software, Live, Max etc and other apps and continue to find surprising uses, and limitations that become possibilities to develop.
Different pedals do things differently - my FC300 sends sysex to the VG so patch changes take forever . . . . however i can send PC messages from the SS and the change is almost instant. Yes the VG has other modes that can send PC's but then I lose the name function etc etc Everything has it's pro's and cons . . .
I realise various people have different requirements, expectations and priorities re choosing this product as well as vastly different musical setups to integrate it into but I truly believe it has a lot to offer and that we have really only scratched the surface regarding what it can do.
<confession>I am a very early adopter of the device wanting one before it was even released</confession>
I keep meaning to post some videos of some of the stuff I have been doing but havent for various reasons . Will be able to now as I just got an ext iSight camera for my iMac.
KMI StringPort_1650, SoftStep_VK2 v1.2 & MIDI Expander; Mac_Moore Guitar,
Roland VG 8, 88 & 99, YamahaVL 70m; OSX 10.6.8, iMac i7 2.8G QC; MaxMSP 5.1.8, Ableton Live 8.2.2, M4L, SC3, QC, cSound, etc, etc,