I owned and gigged with the 5:50 as my main amp for a year.
It has more in similarity with the LSC, as opposed to the LSS. Very Fendery clean channel, with TONS of headroom. Blues/Burn mode on channel 2 are similar to the Mark Series style of distortiom (Low mids, cutting highs). I evntually sold it to finance the purchase of the LSC.
I think it's pretty much British vs. american when comparing the LSS to 5:50