I personally would keep the Mojo and order the DP-X1 to compare the two, which is what I've done.
The DP-X1 is having it's own hype train at the moment, no proper reviews as of yet but people claiming it's better than x, y and z. I'm not saying it isn't and I can't wait to try my one when it gets to me but there is no way way I'd sell the Mojo before hearing the DP-X1 which has had good positive reviews away from the massive hype/fanboy type threads here on headfi. And i mean hype for all products not just the DP-X1.
That is the best way to do it. Hype is real on dp-x1, and so did Mojo hype. However, it is a fact that DP-X1 is a standalone device as DAP and offer Balanced output, where as Mojo is only a DAC and has no balanced output. It is also a fact that SE is inferior to properly implemented Balanced output, and not to mention that DP-X1 has 1 DAC + amp combo on each channel. You will witness the differences in soundstage, clarity, and layering. I also said that Mojo probably is the best from SE connection on sound quality of anything 2x it's price, and in my case that I compared against ZX2, and it really outshines Zx2 in SE, but not in ACG separate grounds connection
I spoke out of my own experiences, what I observed, and for his question of cutting back 1 device so he doesn't lose it. It is a sole good enough reason to buy a standalone DAP instead of having a phone + DAC.