Logitech warranty is pretty legit.

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http://hardforum.com – I had to get my g400 replaced under warranty, I emailed logitech with the trouble shooting I had done and I asked if the mouse was still covered under warranty. They responded with in 24 hours and asked for a receipt and I gave them a scan of it, they mailed me a new g400s (it was shipped the day after I gave them receipts) since the g400 isn't made anymore and they didn't even want the defective mouse back. It was probably the most painless process to get a mouse replaced and I am very satisfied with their service. (Hardware)