Actually I suspect you CAN get radiation poisoning from damaged minireactors. I mean, at one point my character started feeling nauseous, vomited, couldn’t keep food down, in pain etc. Couldn’t figure out what was wrong until it occurred to me to check for radiation poisoning. Had whopping 80 rads or so. The only thing that I could connect to the poisoning was a beat-up atomic minitank that I had been messing with. It had damaged minireactors.
5 plutonium won’t last very long.
Which one is “better” is open for interpretation. Better at/for what? The minitank needs plutonium, which is hard to come by. A diesel tank in turn gulps a ton of diesel. Do you have access to a lot of diesel? The minitank is smaller and more nimble and has easier time accessing places, while a big tank can crush just about anything. Both have their own pros and cons.