And you spend a lot of time messing around with a uC that you will never want to use. Nor will any production house. The ARM chips are dirt cheap and very powerful. Given the 32 bit architecture (there are some 16 bit instructions), you don't need to get concerned about multibyte arithmetic and similar 'features' of the 8 bit world.
Not true, otherwise microchip alone wouldn't sell millions of PICs them every year (not counting AVR) and new and improved parts come out every few months
- altough i don't know how they compare to the sale figures of ARM chips -
The multibyte arithmetic and yada yada yada cans still be issues in the 32 bit world.
Say, you have 16bit timers only that you have to cascade, or you have to perform 64 or 128 bit integer math.
Yeah, the compiler will happily do the work for you and so it will on 16bit cores and 8 bit cores.
You want cheap, robust, higher voltage parts? there are few candidates in the 16 and 32 bit world that meet all three.
I guess i could redesign most if not all of the board we have in production to use 32 bit microcontrollers, but i would have to add the cost of the parts themselves and the added chips, passives and
space for the 5V <-> w/e analog and digital translation
to the OP, in my line of work i have always had the core do a little of integer math, a lot of decision making and fast interrupt response. All can be achieved also in 8 bit cores, i use 16bit cores when i have more complex boards which require more "tasks" to be performed, so every task need little power, but there many tasks.
I won't comment on networking and those kinds of jobs because i rarely have to deal with those things, and in those cases 32bit is my preferred choice
To me usually the CPU is secondary to the peripherals, they do most of the work and the cpu moves bytes around, sets flags et cetera.
To understand the peripherals and how to use them in the non-obvious way for us youngsterns (really opens your mind) i really loved the books by Lucio di Jasio, like "Learning to Fly the PIC 24"
his books are for PIC only, i'm afraid but the concepts will apply for every machine