Yes I have one. Was advised to get one with a specific domed mulching deck (not one of the duel mulch or collect options with a plug for the collection outlet) and they do work.
You can’t try and take too much off in one go though and expect the clippings to magically vanish, about a third each cut is recommended.
It seems to work just as well when the grass is wet if you stick to this rule and as you say it does save the hassle and time of empting. More importantly to me you don’t end up with a mountain of grass cuttings in the corner of the garden that never rots