"working" is an exaggeration. On four of my installations, i have commented out the maxopen/maxidle statements, falling back to the default values of aolserver. So far, i have not noticed significant differences, but its (a) sunday and (b) to early to tell.
Btw, reducing connections from 5 to 1 might reduce memory, but the same time your are reducing greatly the ability to run db-queries in parallel. If you have multiple http requests running, and all of these require handles from the pools, and you have ony 1 connection configured, the queries are sequentialized, since each query has to wait until a db connection is available. This means that he waiting time for handles will go up. If most of your http requests use the database the value for maxthreads must be aligned with connections. On our main site, we have 90 connections configured.