Yes satyagupta, That's possibly what I meant when I said they couldn't be flashed with SimonK firmware. However I did explain that they can be flashed with BLHeli instead. Rather a different procedure needing somewhat more expensive equipment to carry it out.
The Plush range of ESCs are very good in their own right and will power any multicopter quite well. I have two which fly very well using standard ESCs and the KK2.1 flight controller. I do however prefer ESCs flashed with SimonK. I must also add that buying and using the Afro ESCs it is advisable to reflash them with the latest firmware. Even SimonK needs updating.
Anybody wishing to flash any ESCs a database has been put together with all ESCs flashable by using either SimonK or BLheli. Either Google "RapidESC Database or follow this link.
http://wiki.openpilot.org/display/Doc/RapidESC+Database#RapidESCDatabase-ESCSpreadsheetbyTomSn0wThe best of luck to those with the courage to do it yourself.