I'm not too enthusiastic. It doesn't solve a problem, it just makes a particular use-case of an existing mechanic slightly more convenient. While it may not actually impair anything, I don't think it's a wise use of development resources.
1. Collision checks are far harder than programming beams. Take a laggy LAN server, ram a large ship into an asteroid, see what happens. Then take another similar-sized ship and mine an asteroid. Worlds of difference there. Also no clipping with salvage lasers.
2. It doesn't solve a problem, however, I do like the idea. It would cut down on visual effects, if computing power wasn't an issue as well.
3. I can see this getting OP really fast, not to mention laggy as heck when some noob built a planet-sized "system eater" noobcube to collide with EVERYTHING ... yeah.
I can see this being fun, but it'll be laggier and it doesn't solve a problem so it's not a high priority if anybody wants it. I'm neutral - it's interesting but I can see downsides.
The four golden suggestion rules:
First, suggestions don't need to solve problems, they can bring an idea that nobody really thought of or something that makes things more convenient like a better factory system.
Second, When suggesting things, never think about how possible it is for the developers, it limits your creative vision. Maybe you come up with something impossible but because of that, you gave someone else an idea that is possible.
Third, always try explaining when, where or why this feature/fix can be used.
Fourth, after writing the suggestion, re-read it and think about possible exploits, problems and disadvantages. Eliminate them and finalize the suggestion to bring a confident suggestion.
Anyways, I like the idea but the collision detection can't go lower because it always does the checks. Otherwise you'd be clipping through blocks. Reducing the dig speed because of server things would change much in a bad way as the miner will probably be used in small planet related mining operations and having clunky mining would discourage the use of the miner thing. I would love to use this thing for making walkers. It will probably be a thing for later though, once the bigger more major things are in place and when they possibly improved performance for servers.