I have GRLevel 3 and I like it to a point.
Stormlab does give you an added feature, arrival times of what is chasing you.
GRLevel 3 has an active forum much like this one
http://www.grlevelx.com/owners/ and Interwarn
http://www.interwarn.com/forum/forumdisplay.php?f=8 . I think if you read both of them and look at the comments that are there , you will come to the same conclusion I did.
I had Stormlab and liked it very much but I grew weary of everytime something didn't work, it was somehow my fault and being reminded that the software author had another job. He does, he is a weather person professionally and he has responded to everything I wanted or needed.
Now which version to buy of GRLevel? I bought 3 thinking it has all the things I wanted, then finding that level 2 had some options that 3 didn't have.. so I'd go to their forum and ask which is the better, what gives you the bang for your buck.
If I had my druthers, I would have got level 2 and bought the analyst version, but I didn't. I am hoping that a similar version will arrive.
Either way, the feeds come off the same service.. I think Stormlab is a little more user friendly. I think you can download trial versions of both to compare before you buy. I do know with GR.. once you buy it it is yours, Evan Bookbinder will work with you.