Props seem to handle it surprisingly well (at least the titanium(?) leading edges do, the blades themselves can get paint chipped off etc) if you're careful with reverse and feather checks, but everything on the underside of the aircraft, from the rotating beacon (we lost ours entirely at one point), to the blade antennaes (end up cracking, causing a banshee wail over the com in moisture) takes a real beating, as do the flap undersides (look like they've been hit with birdshot, despite being retracted immediately upon touchdown).
Have a beefed up shield made for the beacon, and plan on reskinning the flaps at some stage. Use plenty of blade tape on the antennaes. Keep it out of the rain as well when parked, otherwise they tend to need bilge pumps if you don't want to carry around 50 kgs of water. Plus the avionics/flap motor etc probably don't enjoy working too well when completely immersed in water.
Gotta love it!