Better run for a hardtailed frame than cut the original one.
As often as you changed some parts of your bike, you probably will not like it and than there will be no way back...
And you will get a shorter wheelbase then with the hardtail-kit
See your choice
http://farm5.staticflickr.com/4090/5019917793_211573c6c5_o.jpgand see this one from pangea
http://astraone.com/wp-content/uploads/t...584-900x600.jpg