For my +2 arm I got the longer lines, the place I got them from recomended it.
That said, there are site online that claim the stock lines are long enough. I never put the +2 and stock lines side by side so I can't say the new lines are truely longer.
The advantage of new lines is you should buy the braided stainless and the front brakes will preform better.
If you get new lines buy 2 sets of clamps, 2 for each side. It'll look better and the line then follows the arm well.
I'm running stock lines on my +2/+1 arms and it works but there's not even enough slack in the line to attach it to the a-arm, it has to just hang these suspended by the tension on the fittings. Not really a good setup IMO, just never got around to buying the parts to fix it.
Okay....gotcha, I'll just wait until I install mine and then make my decision.....sooner or later I'll get the stainless braided ones anyway, so I may just spring for a pair now with clamps........thanks fellas