Drum machine (and looper) feature question

[Mark Hamburg <mark@grubmah.com>]

Are there any drum machines available (hardware or software) that 
implement something like the following:

Assuming the common 16-step x0x sequencer, introduce the notion of pattern 
sets consisting of 16 patterns. The currently active pattern, however, is 
independent of the pattern set and is freely available for editing. One 
then adds two buttons to the mix: Load and Save. Hold down Load or Save 
and tap one of the 16 step sequencer buttons to load or save a pattern 
into the active pattern.(*)

The Electribes make a good model for what one can do with a pattern and 
they do have ways to load patterns quickly, but as far as I know, they 
don't make saving on the fly easy. Does anyone else?

And thinking about this further, this could also make for an interesting 
audio-looper interface. On the serial multi-track loopers that I've worked 
with (EDP, Boomerang 3), you switch which loop is both being played and 
modified. In a scheme like this, you have a current loop which you can 
save off and reload to a set of locations. The Boomerang supports the 
notion of saving but not of reloading.

The reason I'm thinking this could be interesting is that one can have a 
current pattern or loop, save it, mutate it, save it again, etc thereby 
generating a bunch of versions that can then be reloaded for further 
reworking.

Mark

(*) My ideal live drum machine would probably also feature variations on 
the load notion to do things like support the SR16's fill notion in which 
rather than switching at the pattern boundary, it switches immediately and 
plays through the end of the pattern — possibly then chaining to another 
pattern.