Is there an advantage to going to a "superline" for my ultra light and light tackle spinning setups ? (4 to 6 # test). Will I see more or less casting distance ? Any line handling issues ? I understand the advantages over mono, especially when used with baitcasting gear. I have no problem with mono, just wondering if I can get the all the advantages of a superline with smaller gear.

Less twist and memory; line will last you years; no stretch; greater break strength/diameter; etc.  Same advantages as heavier braid.  I use 10/2# Power Pro on ML spinning gear for bass, and on longer, slower rods for Great Lakes steelhead.  Since most good spinning reels have an identical spare spool, you can spool that up with your favorite nylon mono or fluorocarbon line to switch when braid isn't appropriate.

Is there an advantage to going to a "superline" for my ultra light and light tackle spinning setups ? (4 to 6 # test). Will I see more or less casting distance ? Any line handling issues ? I understand the advantages over mono, especially when used with baitcasting gear. I have no problem with mono, just wondering if I can get the all the advantages of a superline with smaller gear.

In my experience for the places I fish you 'll see the advantage if you spool in superline of the same diameter ( 4-6 lb nylon diameter ), if you spool in the same pound test but in superline you 'll find yourself breaking lines like mad, 4-6 lb test braided is as thin as a hair and the line is not impervious to the abrassion.

In my experience for the places I fish you 'll see the advantage if you spool in superline of the same diameter ( 4-6 lb nylon diameter ), if you spool in the same pound test but in superline you 'll find yourself breaking lines like mad, 4-6 lb test braided is as thin as a hair and the line is not impervious to the abrassion.

If you switch from 4# mono to, say, Power Pro, you'd use 15# Power Pro to maintain the same diameter. I'm not addressing the question, but 15# line seems to negate the concept of an ultralight rig. And I'm not questioning what Raul says either, about the breakage and lack of abrasion resistance of the ultrathin line.