First off, I'm new around here, but there seems to be a fair level of knowledge floating around, so hopefully somebody can steer me the right way.
I plan on picking up my first pair of skis, something reasonably cheap to begin with in the ninthward B Murdahs from here: http://www.levelninesports.com/Ninthward-B-Murdah-Skis
Long story short I'm really not too sure on sizing. I am about 180cm (5"11) and 65kg (143 pounds) and an intermediate/advanced skier. A few online length calculators rated me at around a 170cm length of ski, not very useful when the sizes are 165 or 175cm. If anybody could point me in the right direction that would be great, I'm leaning towards the 175 ski as I believe they will ski shorter than 175, due to the twintip 'taking some length out' of the running edge of the ski, is this right?