The Moreplay is a seriously good preamp for the money. I like my Cary SLP-05 better but the Moreplay was close to my PS Audio BHK preamp. If you upgrade the capacitors and do a little tube rolling it gets even better than the stock kit. As the OP noted it has a terrific soundstage and great tonality. Biggest downside I found is that 6V6 tubes tend to be noisy and microphonic. Since the volume control is after the gain, adjusting volume lower does reduce the noise but it also decreases the gain which might be an issue depending on what amp and speakers you are using. Bottlehead has announced an imminent price hike so it will only be $439 for a few more days. It goes up to $479 on 10/22. The kit is complete and a very easy build.
What I noticed with moreplay in the system is a bigger more 3d soundstage especially with respect to depth and height, more forward and textured mids (incredible with female vocals), a warmer more pleasing tonality. I really can't believe it. This is also with stock tubes and cheap cabling (the ARC has much more expensive higher quality cabling). Moreplay just brings my system to life and although the ARC is good it makes it sound flat and somewhat lifeless.
I plan to do a full review at some point. I will keep listening but right now I don't really get how this is possible.