Not sure it's more portable, the radias rack is pretty small, and you can use it with a much smaller keyboard (maybe not a nanokey).
The blofeld is also a bit limited regarding knobs, but the lcd graphics are not too bad so it compensates.
I think that my next toy will be somethink like that : http://www.unease.se/img/mfbsynth2mid.jpg , lot's of knobs on a small surface
