Got one of this for my lawn about 8 years ago and it was probably the best investment i've made for the lawn. Not only does it remove the maintenance but it also keeps the grass cut to a certain length, drying out the weeds and fertilising the grass with the smaller cut off parts. On top of that it's electric.

I agree, trees would be better but in your situation i can only recommend it.

EDIT: Forgot to mention, mine been running for 8 years with only 1 battery replacement and the occasional razor blade replacement. The climate where i live is really rainy and it has survived so far.