In my experience, most of the "generic" machines are pretty much based on the same design, originated by Sodick way back when. Don't know too much about that Genspark, but it also looks like the same type of unit as others. Doesn't make it bad, it just states that you'll most likely get the same drilling results.
I have a Perseo Erie 75A unit, dro, programmable Z, and other standard stuff. Not bad, does the job just fine. Looks very much like machines from Charmilles and quite a few others, only the front panel different.
For what you need, that Genspark or most others will be OK.
For ultra small holes, precise spark control, truly clean entry/exit holes, a Current, Astec, HON, or a Beumont would be a better, albeit more expensive solution. Sodick also makes nice machines, but they optimize their control for using an additive called Vitol, which makes everything rather sticky.
If you decide to go new and can get a hands-on test, try a few different materials. See how repeatable is a blind hole test. For through burns what does the entrance of the hole looks like, how much hesitation you get when the trode breaks through the bottom. You'll most likely encounter holes in the .4 mm range, see if you get electrode buckle or burn-up. Many generic machines wont have sensitive enough servo or arc control below that diameter, but I get fairly frequent requests for holes in the .016 - .020 range so you should be able to do that. Check out the ability to bun carbide, and < surprise > aluminum or copper, maybe even Titanium.
