two things are the spice of life, a beautiful woman, and a high bandwidth multi-channel color DSO!
With this scope it has built in signal generator, the square wave output goes up to 8MHz. At 4 MHz the square wave starts distorting but the amplitude stays the same, at 6 or 8 MHz the signal looks completely sinusoid but amplitude stays the same. So I think its bandwidth is over 15MHz because as per schematics http://www.wide.hk/pdf/DS203V2.6_SCH.pdf it uses OPA2354 as input amplifier which is a 250MHz OP-AMP as per datasheet.
However I generated two square waves using FPGA dev board of frequencies in khz, and varied the phase of the other frequency by steps of 200 nsec sweep rate and this little scope displayed it ok. It was not as smooth movement as compared to the TEK 475 but completely accurate. I will try finer resolution and higher frequencies once my VHDL is back (working very hard on it now) to see how it behaves.
Mahmood