They do remove stumps. You just need to take your time about it. In fact, the smaller the machine, the more time you need to take.

There is little difference between the 2-cyl gas and diesel. Except your hearing. You will lose that with the diesel.

Actually, I never dozed with the 2-cyl diesel. I used one for haying. Noisy, noisy, noisy compared to the gas. But hayed better since the diesel had a 1000 RPM PTO vs 540 for the gas. With a 1k RPM bailer, it was half again as fast baling. Had to run it wide open, hence the noise. 2 cycle diesel sounded a lot like following a OTR bus uphill all day....
I don't know about the 1010 diesel vs gas, but suspect it also doesn't make much difference. Someone else needs to talk about that.
Now, the JD 350 diesel was a lot better than the gas. But, that is 'late model' around here.

Stan