I had the 4x model. Was a solid scope that worked great, no issues with the scope itself. But after hunting with it, I found out just how limiting the low 4 power was when trying to get the crosshairs on distant and/or partially hidden squirrel heads. Sold the rifle and scope at later date to fund another purchase. If I had to buy one now, I'd get the variable.
I have the 4x28 on my Marlin 39A. I am very pleased with it. I think it's a great scope for the money. It's not a Leupold but for the money it's a great value. My first 22 rifle scopes were Simmons and after some time I figured it was time to move up the quality curve.
Regarding Simmons scopes Looks like cabin22 came to the same conclusion in this RFC thread. Hey he's from MD. I wonder if he posts here...