In the HE-6 thread, member Armaegis had a mini meet where they tried various headphones, among which the Rag and the V281. He didn't compare them in detail, but at the price, preferred the Rag:
http://www.head-fi.org/t/493214/hifiman-he-6-planar-magnetic-headphone/15375#post_11150289
Obviously there's a hype going on with the Ragnarok, something to keep in mind. I haven't heard either amp (have yet to hear stuff from Shiit that I'm impressed with) and each situation is different but personally, given the price of the Vio 281 can understand his position. I'd probably go for a low power speaker amp like my F5, or for a vintage receiver that's been recapped with my harder to drive cans. The 281 price is just too rich for me, given my sound preference and the gear I own. But obviously, to each his own.