These are the servers I use to host my virtual desktops and virtual servers. They outperform the older Dell servers that only had one system on them. I have about 10 machines on each physical blade. The HP ilo Management Interface is very useful and user friendly.
Room for Improvement:
Blade servers are fading away. I shouldn't have bought these. Overall value is less than traditional rackmount servers. Scalability is limited; restricted by the chassis.
These work great for what I'm using them for, but they are not future proof. XenServer has great features allowing me to have heterogeneous pools. Blades are a good solution for organizations that have limited space and don't want to virtualize.