@KevinJr, I've never had any problems in "liking" reviews - of my business or of clients' businesses. (Not that I do it habitually or anything.)
The reviews aren't more likely to get filtered. Probably the only areas of payoff are (1) "optics" and (2) possibly that those reviews may show up near the top when a customer sorts the reviews by "Most Relevant."
Agreed it could be useless in SEO/Ranking, but that's not my intent, I reply to every review and think the reviewer would be impressed to see a "Like" on his/her review. Thus demonstrating good will and repeat business.
As far as time, it's only a second to Like as I'm replying or have an intern do it.
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