Hi, just joined to share some info. I just bought the 41.5mm to 52 step up adapter and it did have some vignetting with OIS on. Only on the right corners though. It looks like the seller I bought this from made a revision to the adapter, where it now has a chamfer/angle cut into the inside edge to alleviate the vignetting problem. But it still has some vignetting.
So what I did was screw on the adapter tight and marked where the square corners of the original lens opening were. Then I took out my dremel with a long diamond attachment and grinded away between the 2 points that I marked. You have to grind away alot of material at an angle. Now I have no vignetting at all, even with stabilization on.
I use a Sigma uv lens on the adapter and with that on there is no vignetting at all. But I assume if you were to double stack lenses then you will get vignetting. If you want to have no vignetting when stacking lenses then probably the 41.5mm to 58mm is a better choice.
The one thing to note is that if you use an extra lens, then the camera flash will not work properly. Turn auto-flash off.
The seller also sells a direct attachment uv lens, but I think it's better to go with a step up adapter.
Sorry can't post links now, but seller name is below on ebay
Pic shows a windbreaker to stop wind noise, but it also covers the led light which I don't use anyway.