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Tbh, I've found cordless hairclippers more efficient, even at shorter lengths. Main problem is the combs protrude so much that you cant really do the moustache area without it them going up your nose. Also bulkier if you want to travel with them.
I've had an older version of these that worked well until the battery died after a couple of years. The newer lithium ion one should be better.
What length of beard are you wanting to trim to? I've had success with several beard trimmers up to a certain amount of growth, but at around 1cm or more, hair clippers seem to cope far better.