O2, the ER is a built-proof Skimmer with great service, It is not just what you pay up front, I think the others might preform ok even next to the ER. How long will they last and what is it going to be like getting parts for them or do you just have to toss them in the trash in 5 years.
I replaced the pump and rubber on my 5 year old ER 5-2 with just a phone call, now it will last for another 5 years. It is just like brand new and will sell for close to what I paid for it new.
Can you say that about the Octopus or MRC?