Im 5 11 250ish lbs and I ride a 159 capita TFA, whitch is on the stiffer side. at my height Ive ridden larger boards but they feel cumbersome to me. The 159 holds and edge fine and I can rip it all over the mountain no problem. I even ride a 155 for smaller mountain days when I was to mess around in the park and butter.
I'm 6'2" and 230lbs and last season I rode a 155 midwide Salomon The Villain, this season I'm riding a 160 NS Proto HDX and a 164.5 Libtech T.Rice Pro HP with aspirations and plan of hitting allot more powder and off piste riding. That being said if your riding mostly groomers then you'll be perfectly fine, you'll probably be perfectly fine in powder too, but that bit of extra length can help a bit more. Really depends on you and your style mate.
Yeah I found a 164.5 at my local shop on a good discount so I picked it up. I have both boards now and really just need to decide how I want to ride. I'm leaning towards the 164.5 since I've never been a huge freestyle/park rider.