Share port mirroring experiences please

Hello all !!

im need to add a new board to my mikrotik deployment, because i need to setup
som ids and the actual boards doenst have eniugh ports. I have looked at the wiki web
that explains the switch chipset funcionality available and im actually thinking on buying
a RG493G

I would likt to hear from you, your experience with port mirroring and specifically with the
port mirroring rulesets. Could you mirror traffic from a port that is not dependant from the
same atheros switching chipset ?

Performance issues with few mirrorings ??

Thank you all
Javi