Mk3 is better than most solutions out there :)
Discussion
If one is just buying and holding, just staying humble and stacking sats, just hodling for 10 years or so, hardware-wallet signing-devices are kind of optional, correct?
If your plan is to hold for 10 years I would say a hardware signing device is essential. Depends how much you have invested and how large that investment grows.
Due to the $150 price tag any investment larger than 1000 USD in value warrants cold storage on a hardware device in my view.