I started with a 2550, then a couple 320's and lastly a 325.  I disliked the 325 the most. 2550 was my favorite.  The nice thing about you going that route is you can pick up any 2200, 2300 or hs series head with any of those base units. ie, find a head that isn't wore out, off a pull type etc.  I would suggest a 2300 head vs HS.  Never thought the HS would cut as fast. Email me if you want.