I considered this but could not find enough comparisons between the MW and stock to warrant belief that it is indeed better. Different, probably. But different does not equate to better, just different.
Unless updated since I read it, the 6moons review has one obvious hole in it, and that is they did not compare it to the stock TP. Obviously they liked it, and that's fine... but for a 2x premium I for one would like to know what the improvements are.
The SlimDevices forum has some extensive discussion on both sides of this coin. It would be worth a trip there IMO.
I have and enjoy the TP very much btw. No, I have not heard the MW and unless I can get an audition unit I am not about to spend $4K to find out it may or may not be better FOR ME than the stock TP. AFAIK Dan does not offer a money-back deal. Of course that is his prerogative and business model and that's fine.
But many other companies with bright ideas are open to home auditions... RedWine, Zu, NuForce come to mind right away, and I own equipment from all of these. Of course there are likely many others who supply free or low cost (say just shipping) home auditions. This very availability instills confidence in the buyer's mind and opens up a world of discussion possibilities.
To explain that last line above, it seems pretty much the only people who have heard the MW are current owners and maybe a reviewer here and there. Even these, we do not know if they have heard both but it seems unlikely. The nature of humans in general and us audiophiles in particular is that we will praise that which we have a vested interest in.
All of the above to say that I do not consider the MW TP to be a wise choice for someone who has not carefully heard both versions, unless finances are not much of an issue.