I've had the HK85 and groove cutter for some time now and used it extensively on 220x80 baddens for a flat roof build.
Power is surprisingly good, haven't felt it was lacking at any point.
Used it with the standard blade for ripping 6m long laminated douglas beams with the edge guide at full depth, no problems.
Dust collection i find pretty bad. The see through hole on the front left of the saw is there for cut line visibility, but since i've only used it on rails and with the edge guide for ripping, it's of little use to me. I've had it throw saw dust in my eyes on multiple occasions. so be sure to Always wear glasses.
Ergonomics are bad! It's heavy and there are serious problems with the dust hose and rails!
Converting it to the groove cutter gets tedious fast after a few times, but that's to be expected. converting tools always gets tedious. It is what it is.
I haven't had the impression there were problems with rigidity or run-out.
Groove cutter, again little problems. There seems to be enough power for groove cutting in european douglas and canadian oregon.
Problems:
- I have however found the depth to be scale off. I've always had to set the saw deeper by a few mm to get the correct depth of cut.
- the HK guide rails are annoying as heck. The hose ALWAYS hangs on the end of the rail. The saw also oftentimes has difficulty sliding over the rail. I've found that the striped danger indicating tape at the cut line wears and frays, causing the saws difficulty to slide on the rail. I have the same problems with the smaller HK55.
- The dust hose always drapes down and hangs on the rails!!!! I HATE IT. It has caused the entire dust port assembly to break off the saw entirely.
This plastic dust port design is too frail and underdimensioned in my opinion. The hose snags, and your entire dust port breaks off. It's been annoying and in certain instances, dangerous.
But overall, solid saw, annoying to always fiddle and manage the hose when you're holding down the rail and cutting, but I'd buy it again.
I'm more of a Mafell guy when it comes to saws, but the Mafell offerings are twice the price, hence why I got the Festool HK copies.