I do not have one but I have mowed with them and repaired them. It's a nice idea but poorly executed in my opinion. They are hard to work on and covered in cheap plastic. Steering effort is considerably higher than a similar sized tractor. On the other hand they have a couple advantages over tractor style mowers. They have a 4" turning circle, flip up deck(huge benefit), and of course the front mounted deck allows mowing in low clearance areas. I looked very hard at one for my personal use and eventually decided on the Simplicity Lancer. It has a slightly larger turning radius (12") but other than that seems like a much better machine. No complicated cable steering system, ultra simple design, larger engine and deck, better parts availability (shares most parts with the tractor line), and a much prettier cut.
Another downside to both these units is their price. You can get several differant true ZTR units for only slightly more money. This is of course my opinion only, I am not a Husqvarna dealer or owner so I would encourage you to continue your search for owners of the 155 and talk to them about their experiance.
Slam