80%-90% of a good paint job is preparation, NOT painting! Applying paint is trivial!
"it seems to me the most time consuming and effort taking part of painting is getting the right amount of paint on to the roller..."
Couldn't disagree more. A cheap 5-gallon bucket, a grid, a roller and a brush is a cheap, easy, fast and good way to apply paint.
AND... you're painting the OUTSIDE of 2 houses. Rollers are great for getting paint up quickly. But on exteriors, ALWAYS brush it in quickly once the paint is up, especially into openings and especially to create grains.
Your "infomercial" tool might help, but I doubt it ("a tube that holds paint - Huh?"). Two people (one rolling, one brushing) and $25 of parts (bucket, grid, roller, roller-cover, brush) will do a much better job, IMO. And prep is far more important than how you apply paint.