I recently bought a used BladeCenter E chassis, and the seller UPS-shipped it to me with only one inch(!) of foam padding around it. Along the way, someone dropped the 130 pound package and bent part of the case, and one of the blade handles. Surprisingly, everything still works fine!
So, at least on the 'survives physical abuse' axis of reliability, I'm impressed with the IBM BladeCenter.
On the 'easy to find information' axis of support, I've been equally impressed with IBM's BladeCenter support resources. Since I got my chassis used, support involves me reading lots of documentation. Almost every question I've had has been easy to answer, and the questions I couldn't answer involved hardware that IBM hasn't sold in a few years (old QS20 blades).
I've had no problem finding and installing firmware updates, finding tutorials on configuring the networking module, and many other tasks a bladeserver newbie needs to accomplish.
I'm not sure if this helps you with for-pay bladeserver use, but if you go with an IBM BladeCenter, I'd be happy to answer any questions.