I would think they would be ok. I have read dozens of times where people use magnets to cover intake holes on the sides of their barrel.
Hopefully some one else will chime in and give you a difinitive answer. I am still a newbie my self. I just got my first smoker (UDS) built and have only cooked on it once so far.
Take care and happy Q'ing!
If I could I would. If I don't, it's because I am to lazy!
UDS | Brinkman Gasser | Big Poppa Drum
On Deck: Weber OTG