P.U. Potting... Tone difference?

[six foot ape]

Has anyone ever noticed a tonal difference in potted vs un-potted p.u.'s? I've potted alot of pickups but usualy before even throwing them in the guitar (to cut down on how many times the iron hits the pot) but I've never really compared. I just got a Seth from my local music shop and just wondered if I should or shouldn't do it. I play fairly loud and sometimes use a gain pedal depending on the amp and situation and I'm aware of the typical michrophonic feedback that comes with that but just wanted some opinions on the tone of potted vs un-potted.
Thanks

 

[axis2]

I have a pair of Seths that were squealing from cover movement, I was a bit rude when I refitted them so they started to squeal even without covers - clumsy me. I had no choice but to pot them. I can't say that I've noticed any difference in tone but now they're quiet and still sound really good to me. I used bees wax.