Ive had mine for approx 5 months now. It was a choice between the Harrier X and AA S410. I tried both and the Harrier just felt better balanced in my hands.
Magazine is easy to load and use. Cocking mechanism is very sweet - although keep the bolt lightly oiled.
Single shot tray is a nice option for target shooters. I shoot HFT and never really use single shot tray (optional extra).
Just got a silencer (cyclone from BAR as many others dont meet the muzzle of the rifle neatly) and the difference in POI is huge. Thought silencer was causing problems but now Ive zeroed her in it shoots just as sweet. So basically got shoot with silencer on all the time (I use for hunting) or rezero if not using it.
Daystate are a great company to deal with. Tony answers many questions I send via email and they are also helpful on the phone.
Overall I cant really list a fault other than the price of spare mags at £40 and the fact they still dont do a lefthanded thumbhole stock like that of the MK3, but apparently they are due out soon...
Simon.
P.S. Mine is .177
Beretta 692 30" Sporter L/H Adjustable Stock
Crooked Barn 2240 .22