re: Mail in Rebates

Cutting out the UPC will not null a warranty. You just won't be able to return it to the store/online retailer for a refund.

For warranty service, you need only the product serial number and perhaps a copy of your invoice/receipt but usually not.

Yeah rebates are strict but if you follow instructions, it's not that big of a deal. Pretty much all rebates require you to fill out a particular rebate form and mail it along with your original UPC and a copy of your invoice. They'll usually want the UPC taped to the form, and many of them require you to cut out their barcoded address label and affix it to an envelope. Deviation from any of their instructions will likely result in denial -- although MSI actually gives you a second chance to get your rebate if you screw up the first time. Other companies might do this as well.

Maybe it's because compliance analysis is part of my job, but I've never had an issue with rebates.