actually I agree..smaller tanks may require more maintenance or about the same maintennace as a larger tank..but it's relative I consider a 5-10 gallon small. a 20 is what I consider the smallest I would recommend(it gives more otions for stocking.)
I believe that a smaller tank is subject to changes more rapidly simply due to the fact that the smaller environment is more easily changes. an example if you medicate a tank smaller quaratnine tanks need less meds to expose the subject to the right concentration of meds..the same holds true for pollutants.it taks less to affect a change in a smaller environment.
that said , it really depends on what you have time to do.