Cleans on the f50 are pretty good and the distortion is a little more aggressive. With the contour switch engaged, it can get pretty heavy sounding too (almost rectifier-ish but not as loose or throaty), so you really have 3 channels. The Lonestar has better reverb, a little more tweakable clean tone, solo boost and IMO looks cooler, but the F50 is a nice amp too just light on features.... but if you don't need them, don't worry about it.
I hate to say this, when I think F50... I think reliable,versitile backup amp. When I think Lonestar, I think GREAT main amp. Put a pedal or two in front of it and you can get about any tone. But sometimes trades are easier to do, as long as you aren't loosing money you might give the F50 a shot...... There's some that'll disagree, but that's just my $.02 worth.