Some very interesting information regarding this leaked fw that i would like to pass on.
I can report that the leaked fw has worked better than i expected mainly to free up rootfs @142mb (prior was 45mb), and cpu usage is always idling at around 3% (i never overclocked) and the obvious now well tested improvements overall (thanks to people on this forum).
Incidently i only flashed the fw not the emms and all my apps updated straight away with no problems whatsoever apart from 2 desktop icons that were not connected to any app which i simply deleted. I lost no contacts at all or any music or any pics as my memory card remained intact (i did do a backup prior to flash, never needed to use backup).
All of my apps still work and many far better than before.
I can confirm i have actually never turned off my N900 since flashing the leaked fw and have used my N900 to connect to the internet 24/7 (3g dialup apart from a few re-starts) and that i was one of the first 6 people to flash on this forum i believe.
I would say a much better improvement all round than the old fw.
All in all i would reccomend the leaked fw but looking at comments etc it is obvious the next official update may well come before end of May so probably not worth using the leaked fw now if you are in any way doubtfull.

I also can confirm from a source within Nokia that the only reason people have had problems with this leaked fw is because they never cleaned out the old os properly during flash (his words not mine) and that it would never brick your N900 unless you never started with a clean install.
Also the coming update will not be any problems at all to install whatsoever for anyone who has indeed flashed the leaked fw, either by NSU OTA or whatever means you wish to update and it will NOT be necessary to downgrade to the previous fw! and that the new update will in fact completly re-write the os with no need for emms flash (please make a backup before updating).
PS i will NOT give out my contact so please dont ask.