Well, probabbly. an ARM11 700MHz based device would be faster than an e300/400MHZ. From raw computing power I think it should be more than two times as fast as the e300/400 (about 1800 MIPS vs. 800 MIPS AFAIK). Plus the Efika 5200 has some additional bottlenecks.
For the ARM thingie there's the question how the video engine could be used, but it can deliver quite some multimedia content. Seems pretty attractive. Anyway, I guess a 5125 device could deliver quite some fun as well. But it is all rather void: there's no MorphOS for ARM (yet) and no cheap 5125 device.

What I think is remarkable: A never heard of before prototype project gains pretty much PR (I read about that in my local newspaper a few days ago). If, years ago, Genesi would have had that PR with their 99 US$ Efika, maybe more ppl would have bought such a thing. Years ago the 99 US$ Efika was quite attractive. But it had its design flaws (my major critics back then: ATX instead of 5VDC, usb1.1 only), too.