I switched to 4 wheels and I will never go back to 2 wheels. I can easily travel with a full size bag and carry-on now that I have 4 wheels. I can push them with one hand if I need. The other hand sometimes just needs to be free for coffee
I can't say anything about Tumi but I have Victorinox Avolve. They are light and easily mobile. I have pushed them around the streets of Paris and London easily. The only time I seem to have trouble, oddly enough, is on hotel carpets. I just tilt them on two wheels. The wheels have been banged up and down stairs and they are extremely durable. I definitely don't baby my luggage, and the Avolve's have survived for two years of travel.