The only thing I'm aware of that, supposedly, made Linode better, is they guaranteed full compute power. If it said you got 1 CPU core, then that was yours, period. From what I understood with DO, their approach was that they'd make every effort to deliver the equivalent compute power of 1 CPU, but would not peg it to you exclusively. I also think this may have changed for DO.
Where have you seen that you have a dedicated CPU core on Linode?
In the VPS market it's nothing unusual to oversell CPU, you can't only have 24 VM on a single server, that doesn't work financially (except if they count threads from hyper-threading as a core but that's not dedicated).
I've been following my DO allocation using New Relic. When I first signed up, I noticed the hypervisor stealing from my allocation. Not a lot, but some. After a week or two, however, this ceased. I can now report that for almost a year now I have been receiving my full allocation. I am very pleased with DO, but based on the good things that I've read on here, I'll give Linode a shot if DO ever drops the ball horrendously.
I'm not sure of the best way, but I was able to tell by looking at the CPU usage chart when you are analyzing your server. The brown line indicates resources stolen by the hypervisor.
