Hi,
I tested a couple of DC Loads early this year and I still have two here on the workbench now.
Actually there are three, I also have a self-built 200-Watt model that is completely analog in design.
I still use my analog version the most despite having two modern digital devices.
And the reason is that the modern DC Loads I have had in my hands, generate quite a lot of interference signals.
The electronic setup of this DC Loads seems to work via PWM which is not optimally filtered.
Those modern DC Loads i tested are: the Korad Kel103, Rigol DL3021a and the Siglent SDL1020X.
I returned the Siglent because the measurement outputs on the back are a drama, technically very poorly resolved.
The Siglent and the Rigol are actually not good for doing measurements on linear power supplies in terms of their dynamic behavior.
There is too much noise present on the measurement outputs and also on the Linear Power Supply to be measured when you measure with the oscilloscope.
So that is the reason I still often make measurements on Power Supply's with my analog DC Load.
When doing measurements on e.g. batteries or accumulators in terms of their capacities, then you will have few problems with the modern factory's devices.
Another point to be aware of, read the manual carefully if you are going to modulate the DC Load.
The specified rate of current change is hard to get the way you want it.
It also depends on the selected current range and still other settings.
With an analog DC Load you are always in control of the speed.
I use one of my function generators for this and choose the edge steepness as I need it for my measurement without too many limitations of my DC Load.
You can, of course, make the controller the most important thing in your consideration, but that,
in my opinion, is the electronics in your DC Load must be able to do the measurements properly that you want to do.
You can have wonderful control functions for your DC Load, but if it doesn't do what you want, it's a waste of money.
Ik hoop this helps,
Kind regards,
Bram