Japanese maples including dissectum varieties transplant quite easily.
Not particularly good for bonsai in my opinion. - tend to have longer internodes so ramification will be coarse, also prone to dieback of branches.
Whether this one will be worth while will depend on the trunk and branches and what you expect from bonsai. Looks like just a couple of really thick trunks with little taper. Branches are probably all near the top? Again, depends what you want your bonsai to look like. Trees that look great in a photo inevitably look far worse when seen in person. Trees that look great before digging are nowhere near as attractive once you get it out of the ground. After potting they are even uglier. After a couple of weeks you will wonder why you ever bothered and start planning to get rid of it.
Size: Looks big! Consider: What sized pot will it fit in? How will you manage it in future - rotating the tree every week or 2 to get even light on all sides; repotting every few years; where will it fit in your garden?
Be warned, trees seem to expand when dug. A reasonably sized tree usually turns out to be about half as big again when you try to pot it. It will weigh about twice what you estimate and will never fit in the car you hoped to take it home in.
Very occasionally one will be just right. That one will make all the others worth the effort and anguish.
Any freebie is worth collecting just for the experience and to develop skills. If I had the opportunity and the space for this tree I would probably take it.
Those are just my observations from many years of collecting trees for bonsai. You are welcome to accept or reject any or all.
Thanks for sharing your experience with me.
From my experience on the two digs I have done, one was super easy (lonicera nitida), with small enough ball I managed to jam him into a colander. Other dig was a mature azalea in the rain, super heavy ball of mud nearly equal to the size of the foliage, had to be put in a large crate.
So I could probably use the experience.
I'm going to go dig. I could use the excercise and beautiful day today, 50*f and sunny. I appreciate the diversity of comments, and would like to thank everyone for contributing to my learning.
Now do I do my chops now, or wait until next appropriate time for a.p.?