In my experience it takes much more work to keep them well maintained than to keep a canister or large HOB going. Even well maintained ones seem to usually end up with problems a couple years down the road. The 90 at my work is a prime example. It was well vacuumed weekly and was RUGF and still ended up loaded with debris. For the money there are much better options. And since so few people maintain them as well as you seem to, it is even less of a good option.