Personally, I've had some hell with Cirtex Hosting. I also feel they fall in line as being a "nickel host."
During my time with them, the support was sub-par and their servers were always under-fire. When I finally had enough with them, I moved off to another web hosting company, but leaving them was a hassle in itself. The support team seemed clingy on trying to keep me, I only managed to cancel my web hosting package when I agreed to let them manage my domain name. A mistake, since they later decided to not issue me an invoice, and not allow me to pay for the renewal. They also would not answer any of my support requests.
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