Hi,
So from your reviews I see that you are satisfied with CP2100B, but not with CP503B?
Yes and no.
The CP2100B costs little but offers good performance.
The CP503B is not bad, it has much less noise than the CP2100 and is therefore also suitable for lower currents.
Its significantly smaller size is also an advantage.
But it has an unstable bandwidth and is quite expensive compared to its performance.
Or let's put it another way:
For the money, I would rather buy a used combination from Tektronix (A503/A6302), which is simply incomparably more stable in terms of values.
It has 50MHz bandwidth so that should be more than enough for switching on/off currents in smps?
Absolutely.