We have a hosted dedicated server, and we're looking at adding another one. We think our current provider is a touch expensive, so I'm also gathering quotes from other providers. I was asked if we should leave our original machine with the original provider and get a new machine with a new provider -- the idea being a kind of risk management.
My impulse is to say no, because then you've got two bills to pay and two admin consoles to use. Plus, there are services on the first machine (database, webservices) that we'll want to call out to from the second, not to mention copying large files back and forth occasionally.
Is there any argument for splitting machines across providers, apart from the convenience factor of not having to reconstruct the original machine at the new site?
/Edit - the answer below assumes that we're talking about a production application.
It entirely depends on your application. From what you're asking, the answer for you is "no." The answer for other applications may be different.
If your architecture can't seamlessly handle being active in two locations, then don't try. You're not managing any risk if the second site is dependent on the first, you're merely adding additional points of failure.
Given the additional parameters added after you posted your initial question it would not benefit you to split apart your dev and production servers across two hosting companies. Hosting companies seem to have different settings and environments literally for each company. If you want to simulate your production environment then leverage the same hosting company as your production environment. If the current cost is too much you can always go down a level for both production and development environments.