We've bought a handheld Dymo LabelManager 280 for our Hackerspace. We've tried third-party labels, but we'll be back to official ones. Not because the third-party ones aren't supported - they very much are! It's because they turned out to be shitty; the quality of print is quite bad. Not a showstopper, but you don't spend money on a label printer to have shitty-looking labels everywhere.
And I'm not necessarily against using that information to void the warranty too.
In the US a manufacturer can't use a simple indicator like "you broke the seal" or "that's not an Original Manufacturer cartridge" to void a warranty. A warranty may only be voided if the specific act involved was the actual proximal cause of the failure of the product.
Anyone who tries to use "that voids the warranty" is usually just trying to invoke FUD with no legal standing.
"Warrantors cannot require that only branded parts be used with the product in order to retain the warranty.[7] This is commonly referred to as the "tie-in sales" provisions,[8] and is frequently mentioned in the context of third-party computer parts, such as memory and hard drives." [Wikipedia]
Edit: Additionally, the onus is on the manufacturer to prove that a non-OEM part or service was the proximal cause of a warrantied failure. They don't get to put it back on you without proving their case.
[1] https://en.wikipedia.org/wiki/Magnuson%E2%80%93Moss_Warranty...
"Our records show that you had the oil changed at a third party, which we do not support. As a result, we are unable to repair [unrelated powertrain failure] under warranty."