There have been a couple of queries recently about connecting switches to analogue inputs. (Phil Broome)

The main issue will be response times as the analogue inputs are only checked every 4 seconds (1 input a second). Therefore if you want to connect a switch operating lights or similar this will not respond at a reasonable speed for a general user. But if what you need to connect is something like a level sensor that changes relatively slowly and whose input switching is long term then you could use it.

For similar issues devices like PIRs could not be connnected to the analogue inputs as they generally generate a circa half second pulse on the output.

This has been taken on board and a future release of firmware will up the sample rate and will also do a little bit of averaging to reduce noise.