Easy guys, I was just asking for opinions and that's what I got. In the end it's up to me to try and form my own opinion from yours. No harm done yet 
Okay so what I've found is that if you ask 10 people, you'll get 10 different opinions. Of course it all varies depending on how you've built these scenarios and worked with them before. The solution I'm tending to lean towards this far (meaning I haven't really decided yet) is this IP SAN:
And one of these switches for backbone:
High-speed 10 Gigabit Copper switching for small to mid-sized organizations
I'll also need to put in 10gbe cards in all three servers. In total, that puts me at just over $6000. I've been using QNAP for years and never been disappointed about support or support hours, or the quality of their products.
Why I'm leaning towards external storage:
If the external storage goes down I can still revert to backups that resides on the backup NAS. I can even run them from there, although it'll be slow I'll still minimize downtime. If a single unit server goes down though - "no hablo", unless I keep an aging box that won't be able to run 12 simultanious guests anyway. With 3 servers, if one of them goes down the other two can share the increased load until I've ordered a new cheap low-end box. In the end I think I've saved both downtime and money. Just my personal experience / educated guess.
But as I said, I haven't decided anything yet, I'm still evaluating all of your opinions and are trying to do my homework