I bought one of the early ones in .177 - it was utter rubbish! Great looks, great shot count, crap groups. Tried everything but nothing worked so I sold it!
Personally I wouldn't buy any FX in .177 with a smooth-twist barrel for sub 12ft lbs. Maybe they are OK at FAC velocities and are probably better with the meatier .22 pellet but I don't think they work well at low pellet speeds, especially in .177.
I tried a whole pile of different pellets, of all the best makes - nothing really improved the poor groups.
Also with the Impact - the majority of the adjustments available for FAC versions are disabled on the UK spec rifle.
Check out Giles' (Airgun Gear Show) review on you tube - I laughed when I watched it - sorry Giles it confirmed all my tests! Those groups are not good!
If you want a really good, accurate rifle try and get a new Daystate Airwolf, or a Mk4 is, or a Daystate Pulsar - I've had all 3 in .177 and I assure you they are amazing.
ATB
Jack
Steyr LG 110 2014; Steyr Pro X; Anschutz 9015 HP ; SCR Exile .177; FX X barrel .177 Aeron Streamline; Daystate Delta Wolf .177; Tau-Brno MK300 .177; Sportsmatch GC2 mk3 .177