I've been tempted by the W3K but I still love my W1000X and wouldn't want to sell it. But if I had W3K, I'd probably never use the W1000X... so it would just sit there taking up space (which is limited for me). Bad reasoning, I know... Also, I want to get back into Stax one of these days and that means getting rid of other things rather than buying more.
I'll be honest and say that after I purchased the W3000ANV, my W1000X (after going through the trouble of modding them with L3000 leather pads and also applying a minor dampening to reduce the booming bass) have not seen any use in the past year. It is a pretty wise choice to avoid buying the W3000ANV if you're already happy with the W1000X.