Interesting topic as I am currently dealing with the same issue. I've been checking out MBA's in the past months and right now I'm in doubt between applying at IE (PT), St.Gallen (PT) or Insead (FT).
I attended an information afternoon at HSG two weeks ago and I am actually highly impressed by the PT programme. The structure with fixed monthly modules allows a lot of flexibility and the modules abroad give an extra touch to the curriculum. There seems to be a good class atmosphere, with people also meeting up outside of the modules. The average pt students is often an expat already working in Switzerland, so the changes of living in close proximity of your fellow students (i.e. Zurich) are quite high.
We also got more information on networking and career services in the PT programme, apparently this will be improved for the PT students starting from this year, so one will now have all the benefits and possibilities of the FT programme (if you want to of course, some people decide not to change jobs). From what I've been told, recruiters don't seem to make much difference between FT and PT, although you could use the PT as an example of your time management skills. Either way, at HSG the career service departement puts the student profiles of both programmes together, no real distinction there.
I am not familiar with CASS, but in my opinion the choice between FT or PT (in general) should depend on your financial possiblities and on whether you want to accelerate your career or make a real change (position /industry /location).