i've had all my sites hosted with RS. Everything was working fine until it didnt. The machine they hosted one of my sites on started having issues. One my site was went up and down and there is no way i could do anything on my end in terms of changing machines since i had a ssl certificate locked to the IP. RS is really inflexible in that it can not remap ip to any of your instances.
At one point, i did a backup of my instance and it got stuck due to a bug. The delay caused their scrub service to wipe clean my whole instance. My main site was down for about 15h. Support during this time was always the same answer "We're looking at it and we'll have a fix ready soon". There were no fix. I lost tons of data, customers, and money. I asked for a refund, but all i got was a tiny credit only. Not even close to the the time and cost i spent reviving things.
Rackspace sucks biiiiig time. their code is probably all poorly designed, spaghetti code. I recently joined a company that is using swift (rackspace implmented). Thats the one flaky thing in our environment.
bottom line: DON'T