don\'t have your 7K but used one on my D300 as main lens for last three years and loved it,, about 80% of my photos,,
the 17-55 is a gold ring lens and believe Nikons gold ring lens are dust and waterproof (to a degree) have used in rain and considerable dust with no issues,,
I have used the lens on my current 800e and can tell you the lens just keeps giving the quality anyone would expect,, of course it has recently been replaced by my 24-70,,
if I ever went back to DX the 17-55 would be my first purchase for the camera,,
