Threshold recording and the loop oriented drum machine

[Mark Hamburg <mark@grubmah.com>]

Does anyone know of a drum machine (or the software equivalent) that  
will allow one to dispense with setting tempo and length and instead  
let one do the following:

1. Hit Record to prime the recording process
2. Actual recording begins when you first hit a pad/note
3. Hit record or overdub to end the loop

Tempo can then be defined based on a fraction of the loop length  
(possibly with some form of intelligent auto-detection).

I've found that I can easily play a pattern and hit a button  
essentially meaning repeat which effectively closes the loop.  
Everything else is doable but takes more concentration on issues other  
than the general flow of the pattern.

I can do this with my EDP if I live with mono results that can't be  
edited as MIDI data, but this seems like the sort of thing that ought  
to be easy for a MIDI-based device to support. Are there any that do  
so? Do I need to build my own sequencer -- I've really been resisting  
writing my own music software since I spend my days immersed in the  
software industry.

Mark