I would edit the above post, but it doesn't seem to allow me to.
Was able to play with sugar on the pi using the default debian build. It's functional, but the activities available is just a small subset of fructose (the default set of example applications). I'm going to try getting jhbuild setup on my pi to download and compile the entire current sugar environment plus applications, make sure it's properly optimized for armhf.
For those who want to try at home, I did an "apt-get install education-desktop-sugar", but that installed a whole bunch of unnecessary desktop items along with it (like cups, and some mail transport agents). The final version of sugar installed was also only 0.88, when the current stable release is 0.96.
It's my intention to build a rpi specific build of sugar 0.96 with all the required packages and activities included, that doesn't pull in extra cruft. Performance of 0.88 seemed decent, could be faster, but I'm betting a lot of that would have to do with the lack of HW X acceleration, or optimizations that might be possible with the python layer of sugar (which seems to be eating up most of the CPU time when apps start).
But, while not perfect, I'm pretty sure a 0.96 build without any further optimzations would be 'good enough' to give to my kid to play with.