Recycling? - Not as of yet we are looking into that, but the plastic handle and aluminum guide plate could be recycled locally. Others have asked about replacement blades, as of right now the blades are by far the most expensive part of the product to manufacture and it would not be cost effective to offer replacements and it could introduce blade alignment problems.
Many people do use it as you describe when they don't have time, pro-shop isn't open, or are too busy and they are able to stretch out the time between sharpens significantly.
Downsides? - It is not idiot proof, it is a manual tool - it takes 5 min to learn the right pressure (start very very light) and to keep it flat on the side of the runner, 95% of people have success with their first sharpen.
We have had some testers use the tool exclusively for three years (on ice twice a week) and we saw no increased wear as compared to a machine sharpen.
If you use the same number of passes on each edge you will be fine. But yes it is a manual tool and if you used it exclusively an edge checker is a good idea or just periodically get your skates machine sharpened.