SATA Drive Replacement on Dell PowerEdge R410
Solution 1:
Yes, the Dell drives are special -- they cost a pile more, have a Dell warranty, and your rep probably gets a commission out of selling them, all of which you don't get if you don't buy Dell hard drives. (Whether those are benefits or drawbacks I leave to your own best judgment). For the record, we run aftermarket drives in our R410s (mostly SAS, I think) without a problem, using the same trick (buy cheapo drives, remove the caddies, use drives for target practice on the clay pigeon range).
Solution 2:
It would be unusual for DELL to be using some sort of proprietary drive. The sales person may be referring to "enterprise" SATA drives which often times have firmware that helps when being used in RAID.
For example, Western Digital has a feature called TLER (Time Limited Error Recovery) as listed here: What is the difference between Desktop edition and RAID (Enterprise) edition hard drives?
Solution 3:
I don't see anything in this Dell Technical manual that rules out using any other brand of drive. Pages 29 - 31 are the relevant ones. It says you have to choose hot-swap or not when you buy the server and from the pictures it looks like if you go w/ cabled there'd be no problem using any old drive. If you go w/ hot swap, you'd have to do what your said - take their drives out of the trays and put your own in. That'll void your warranty, of course...
Solution 4:
The service manual doesn't seem to mention anything about special drives. Usually, I will check the manuals for a given server before I purchase it or trust the salesguy. I don't have any 410s, but I didn't have any issues replacing drives on a R300.