I would agree that for * the most part * you would take the stats on your ranged slot, for the obvious reason that rogues are not a range-heavy class, and it isn't going to be a reliable source of damage.. so the stats are better allocated to boost your main source of damage, melee.
HOWEVER, it is my opinion that a thrown weapon is > the stats of a bow/gun for any serious play, simply because the cast time is so much faster. The health pools in this bracket are small enough that, for the most part, one heavy runecloth bandaid is a full heal - and that small cast time ( vs the larger one of a gun/bow) could be the difference between you winning the duel, downing the EFC, or not. Especially if that EFC is someone good, you simply don't want to give them the benefit of an extra bandaid tick or two before it is interrupted. It is also much more likely that you will hit a druid/rogue running away to stealth with a thrown then a bow, just because you give yourself more of a cushion on the timer.
So, the reasons are:
-interrupt bandaids \ pushback on heals
-keep opponents in combat
You could swap out, but as stated that cast time is what I am looking at, I personally think it would be a waste of a GCD. So, pick the BiS thrown & ranged weapon for you, and use them accordingly.
Just my 2c,
Volsci
EDIT: upon a reread.. I just realized how heavily towards a bow/gun that sounds. I meant to come across that if you don't care about BiS/serious play and just want the highest stats \ damage, pick up a bow\gun. If you are playing seriously at all, use thrown.