Most of the forum and wider web talk seems to be about smaller linodes, I haven't seen anyone mention larger use and in fact there are external forums that say once you get past a certain size, why not just get a dedicated? Cost is one answer (I'm not interested in bargain basement dedicateds). Any thoughts/experiences?
It's also a lot easier to split up your stuff across multiple instances. You could have your database servers on large nodes, serving stuff to application servers on smaller nodes, knowing that everything is on the same grade of hardware and that you can add application servers without waiting for someone to provision hardware for you.
One I would check out for large VPS allocations would be Storm on Demand. They offer 32 GB of RAM, 1.5 TB of disk for $350/month. (Bandwidth is extra and can be pay-as-you-go - still free inbound).
(Sorry, Linode. I love you guys but it is true about the larger plans)
Traffic for my Linodes started at around 10,000 pageviews/day and now is around a million for mixed PHP/MySQL content, sites, and applications. In fact due to a miscommunication between me and my junior designer, a page element was pushed into production with the content hosted on the two small Linodes before I had a chance to upgrade them - moving from 20,000 pageviews/day to around 700,000 pageviews/day. I still don't know how, but they held up just fine until that evening when I upgraded and added the third server.
What I'm getting at is that yes, you'll see consistent performance. I've been a Linode customer for, I believe, about 3.5 years now and that's one thing that has impressed me about them - consistency.
I have all 8 machines pegged at 100% (or 400% if you like) cpu for a quite a lot of the time every day, and normally am doing about 4k block/s on the disks. That said, with how batch oriented hadoop is I'm not sure I'd actually notice a little performance blip here or there.