"I am currently booting ESXi from a USB drive and storing the VMs on the 250GB drive which came with the N40L. Am wondering if other guys have a similar setup with these boxes?"
I am using the 250GB that came with it as my datastore, I really did not see the point of installing esxi to usb to save a few gig of space on the 250GB drive that esxi requires. Depending on your setup usb might make sense, say for example your host did not have any local storage.
So your running embedded version of esxi vs installable version? If you were going to setup a raid array for your datastore - sure use usb to boot esxi so that its not installed on your array, etc.
But sounds like your wanting to do what I am doing.. Using a VM as a NAS/Storage/File server - which you have added disks to use as space for this VM. So raw should be an option for you just like in my case. These other disks are not going to be used by another other VMS - they are just storage drives. The 250 is my datastore drive - this is where all VMs OSes get installed - and to be honest 250GB is a quite a bit of space for just VMs that are just test/play boxes and not serving up data. For example my pfsense has a 8GB drive assigned to it on the datastore, and that is over kill
My linux shell box also has 8GB, again overkill for what it does. w7 I gave 40, again overkill and setup as thin anyway -- if your going to be storing data on your storage Vms other drives.. 250GB is quite a bit of space
Did not see the reason to save a couple of gig by installing to a USB. But it really shouldn't matter which way you go from a performance point of view of esxi, other than maybe bootup time. I would have to hope mine boots up faster than yours off sata installed hdd vs your usb