Magneplanar MG-1.7, MG-3.6R or Sonus Faber Liuto - Advice needed.

I have a pair of 1.7s that I like a lot.  But I've got the never satisfied urge to find the next step to musical bliss.  Would the Sonus Faber Liutos be a significant step up?  Should I buy MG-3.6Rs?  I'd appreciate any help from people who have experience with these speakers.  Thanks