This is a fair question. I am really torn with all the amazing headphones coming out. I really do like the M4U2, but I suppose it is the promise of something better around the corner that is causing hesitation. I purchased and returned Amperior based on A/Bing with the M4U2 and determined the M4U2 was better than Amperior in every aspect regarding their sound. I also ordered and returned the Denon D400 and D600. Returning the D400 was a no-brainer as it is simply horrible. I A/B'd the D600 against the M4U2 and they are very different sonically. The D600 is superior in resolution and detail which made a significant difference regarding the transparency of vocals. However, the M4U2 was far superior with bass punch, depth and presence. So, I am still looking for a headphone with even more upside on the bass than M4U2 with the resolution of the D600. I am waiting to see if the M-100 will live up to that hype as the early CNet impression indicates it might. I also have my eye on the Momentum, Yamaha Pro500, AKG Tiesto K267 and Ultrasone Signature DJ. Most of these will be out by the beginning of October, so I plan to make a final decision then and to have the M-100 in hand for comparison. I will also consider the M4U1 since I already use a FiiO amp and don't need the extra cost and weight of the amp in the M4U2. I don't know that there has ever been this many new options at once for quality, portable, closed circumaural headphones and I want to carefully make the best choice for my needs. V-Moda has a 60-day return and if they are not as good as expected, I would not hesitate to return them either. My loyalty is to the company that gets it right and produces the headphone that sounds best to my ears, but I have become somewhat of a V-Moda fan after auditioning the M-80 and seeing how involved the CEO is regarding interaction and feedback from Head-fi members. In terms of headphones under $400 that are available for purchase as of 9/21/12, I will still state that the M4U2 is one of the best options available and the best option for audiophile portable use.
I used to do a very similar thing with my computer builds...I'd read about video cards that I knew were coming out in a couple/few months, and about the new CPU/Mobo/RAM combo's. Many of these "upcoming" items always had me many steps behind my friends, but at least they were usually cheaper when I bought. This is all OT, but I can certainly see why you'd do some homework when spending so much on a product like headphones. These are personal items that will (read: should) last a long time, so it should be important for you to get what works for you and your life. I applaud you for your discretions!
As it turns out, I'm leaving the city into my own home in the country where I'll only be using my cans on a minimal basis (at least that's what I expect) as I have a very nice sounding stereo system which will get used much more.