I have tried some waveforms and sine is perfectly usable till 10 MHz as specified. The square one is usable till about 8 Mhz, then it become a little distorted.
The other ones are prefectly usable till 1 MHz.
I do not have a MHS-2300A, but which one is better it depends on what do you want it for... MHS-2300A has 2 channel, GK101 just 1, GK101 is smaller and has a touch screen interface that is really easy and intuitive to use...