I have been reading about Berkley Vanish line and its uses for Dropshotting. I recently went to Walmart and found some 2lb test spools of Vanish for $2. Would this work to test the theory of Vanish VS Ordinary lines or does that line just seem too light for dropshot application?

2lb line is, IMO, a wee bit on the light side for dropshotting.  I use 10lb SilverThread.  Pros seem to use anywhere from 6-10lb.

2 lb is fine if you are dropshotting for bluegill.

I wouldnt go any lighter than 6 lb.

B

I use 8lb for dropshotting

AL

You could always go with Yo-Zuri Hybrid Ultra Soft.  I has a breaking point much higher than the "pound" test.  I think the 4# is something like 6 or 7 lb breaking point.  You could PM Roadwarrior and he would be able to get you much more accurate information on Yo-Zuri. I use 6# on one of my reels and have never really had much problem with breakoffs with it.

I use 8# P-line Flouroclear for dropshotting. Great line at a great price , it allows me to change line frequently or as needed.