I started by buying a IVSO Flex Case-Book Case Cover for ASUS Transformer Book T100 Tablet leatherette. It is with this tablet case is discharged extremely quickly in standby. With the slim smart cover over the problem, the standby system (Magnetic I think) works fine. Probably because the slim cover is adjusted. I did not see any particular problem due to the fact that the Micro SD card is not accessible when the installed protection. I feared she would ejects pressure but this is clearly not the case.
I have not tried to connect the keyboard when the cover positioned but with hindsight I doubt the interest of a pouch for tablet + keyboard: If the keyboard is connected to the tablet screen is naturally protected.