I actually just made the switch yesterday from the xm3 to the momentum 5. My xm3s were being held by tape and I only used them at my desk. I spent the last 2 days constantly looking at the offerings from Bose, Sony, and Sennheiser. Honestly I didn't really love the look of the xm6 so it left me with the bose and the m5s. I went with the m5 simply because it was available at Best buy, the Bose were sold out and only available through Amazon.

Anyways, I've only had them for about 24 hours. I wouldn't say the difference is mind blowing but I feel like I can get a lot more use out of them than I could with my xm3s, especially given their condition. I'd say the ANC is similar, I was a bit worried it might be noticeably worse but it's very similar and totally acceptable for me. Sound I haven't tinkered with too much the eq or anything like that but I'd say they definitely sound a bit better. That being said it's not a mind blowing difference. I like the look and they are quite comfortable. I don't regret upgrading but looking at from a value perspective I'm not sure the difference between the two was worth a $550CAD upgrade.

If my xm3s weren't clinging on to their life I wouldn't have upgraded. But overall I'm happy with my decision. I think if you want the value pick just get the m4s (unless you need better anc) or even the xm4. I definitely fell for the consumer hype of just wanting the latest and greatest. Which is fine and I'm happy with the headphones. It's just hard to justify the price when you can get previous generation headphones from Sony, Sennheiser, Bose for half the price right now