I am a client from Nexcess for around 18 months, I had some issues in my web store during this time that were unrelated to Nexcess, and luckily using the support from Nexcess all of them got resolved in no time.
I have to say that the staff working at Nexcess is just great, resolving issues beyond their scope of services, professionally and promptly. (Just no down time in my web store)
Besides the hardware in place, which is important, much more are the people behind this hardware and Nexcess have them.
I pleasure to be a client.