All of these are tank type units, not what the OP is asking about. I too have a 2½ gal Titan (the dark blue one) under my sink.
I have looked into "instant" units and concluded that I need a decent sized one to do what I want. I need to be able to raise the temp of my water from about 50°F to 105-110°F with a 3 gal/min or so flow. To do this will take one that is in the range of 13Kwatts. I want to be able to fill a bucket with hot water.
The one the OP shows comes close, but will still struggle to do the job. It will probably do great for low flow handwashing, however.
For now, I'm happy with my old tank unit.
Charles