It won't print with any 3rd party labels at all, and it also didn't work with the official Dymo labels provided with it, do not buy.

You thought ink cartridges were bad? Dymo out did them. This new model will not print on anything other that Dymo branded labels (2x-10x price of generic ones). Just imagine if your printer prevented you from using standard reams of paper, absolutely ridiculous. There is reason to buy the new 550 range that outweighs this anti-consumer design.