I have not had to send my 300D in for service, warranty or otherwise (famous last words). However, this topic has come up plenty in the past year. By all accounts I'd ever read or heard of, Canon merely flashes to latest factory firmware revision as a matter of course in their repairs.
Here in the US, I believe Canon would have to clearly demonstrate that the use of a third party firmware was a clearly stated violation of warranty terms OR that this was a cause for the need of repair. For example, your autofocus dies, mirror breaks, LCD goes dead, etc.
The following is based on my firm opinion, developed by my reading of the following documents. I am not a lawyer, though I like to play one on the Internet. ;-)
Read here:
http://consumer.usa.canon.com/ir/controller?act=PgComSmModDisplayAct&keycode=2113&fcategoryid=215&modelid=9430
And here:
http://www.ftc.gov/bcp/conline/pubs/buspubs/warranty.htm#intro
It's not difficult reading, actually. A little dry, but quite clear.
I would conclude from Canon's written warranty that the "hack" does NOT consitute a violation of warranty terms as set forth in their warranty. It must be stated, it cannot be 'hidden' (that would be unlawful). I would also conclude from the "Magnuson-Moss Warranty Act" that Canon would be legally obligated to honor the warranty on firmware 'hacked' Digital Rebel (NOTE: This would not constitute 'modification', which is intended to void the warranty for reason of PHYSICAL modification, not the running of a different firmware! -- only in the case of the FIRMWARE being the reason for required service would Canon be legally able to deny warranty service to you).
This would explain why everyone, at least everyone I've seen post on this topic, merely had their firmware reset to the latest Canon firmware during service. Canon really wouldn't have much of a legal leg to stand on, in denying legitimate warranty service to someone using the Hack... UNLESS the hack was the REASON for service (ie. camera locks up on reboot, unable to flash to Canon firmware, reason found was use of hacked firmware causing lockup -- BEAR IN MIND, this has NOT been an issue with the hacked firmware. It's widely in use with excellent, reliable results).
Call Canon and ask them (not a Customer Service Rep, but someone in their chain of Management team, relating to Service). Ask them to state for you their legal position on honoring a warranty service request for a Camera using unofficial firmware, when the repair service is NOT due to a firmware issue. I haven't bothered, my Camera is now out of warranty, but during my warranty period I used the hack with the utmost confidence in my rights to obtain warranty service.
Best of luck (ps/the hack is safe, reliable, easily reversed, and VERY well tested at this point).
icmp
Been reading the threads about Canon not releasing a firmware
update for the 300D. So I was wondering if any of you have
installed the hack and later had to send your 300 in for service.
Not because the hack made your camera crash or anything lets just
say something broke.
So I guess my real question is, What did Canon do or say about the
hack being on the camera?
Spiff