Wooo, i've been waiting for this to be released. Do you have a link to the site announcing the release, i've just check a few sites quiuck and havn't seen any big notices. As for working on the Simply, I see no reason why it shouldn't. Though I will be buying one of these (providing the price is ok), so I can confirm it's compatibility when it arrives.
from what i hears: -variable rumble (3 settings) -the thing has 32MB of ram with the same signature as the ds browser expansion cart... wonder why... hehe. -currently only works with ezflash V(5) ->will work with other slot-1 models in the future -doesn't take external memory, rather, it downloads from slot-1 into its 32MB of ram, which means... GBA COMPATIBILITY! [downloaded from slot-1] -around 22$(US) k byeez
That would explain why it will only work with the EZ-Flash at the moment. I think that the Rumble and RAM features should still work with the Simply though, as, like you pointed out, the RAM uses the same signiture as the official one.
there has been hombew develpoed at gbetemp and sosuke.ezflash.com that allows the r4 to work with it...
so this oly work for EZ Flash V for now, and if you guys want more information just go to the official website ezflash.cn/en