In the system I'm working I have several tasks like checking keyboard, refreshing LCD, reading several analog channels, making some PID calculations and drive some outputs based on some inputs.

I can develop a SW without a RTOS and multi-tasking mechanism. In this approach I run some functions periodically within a timer interrupt and do other -unimportant- tasks within the idle time in main().

Using an OS with multitasking support seems nice and simplifies the programming.

Since I do not have any experience with a system based on a RTOS, can anybody give me some idea on the cons and pros of using and not using OS/multitasking.