I finally got my PL21's from FocalPrice, and I don't have much to say about their SQ: of course this is entirely subjective but I find them better than my PL30. I find them a bit more bassy but with better midrange and much much more comfortable. Moreover, the PL30 took hours to stop sounding like crap, and these ones only took minutes.
In short: I prefer them over the PL30 in every aspect.
I have a word about comfort, anyway. I supposed that the PL21 were designed to be worn with the cable straight down, and it was a thing I really liked because I hate wearing the cables over the ear (it keeps jumping over my ear and that's very uncomfortable). The angle of the tips were strange for that kind of wearing, but... So I tried to put them in my ears with the cable pointing to the floor
It was painful and uncomfortable, and when I finally could put the darn drivers into my ears, they totally lacked bass. No basses at all, and I think it is because the vent hole was covered by my ears when I wore the units with the cable straight down.
I sweared a bit and after some capital words I tried them with the cable over the ear. Usually I have to pull my ear up to allow IEMs to enter my ear canal properly, but not this time: a gentle press with my finger and the PL21 fitted perfectly. With the cable over my darn ear... Well, lesson learnt: don't assume that an IEM is not "over-the-ear" from the photographs.
Of course they can be worn with the cable straight down, but the angle is not good to enter the ear canal properly in my opinion. If the angle could be reversed by disassembling and reassembling, that would be another matter.
The cable is a bit different from the one in the PL30's, and looks like it wants to stay over my ear and not jumping out, but I have to test it more time. I don't want to use the rubber hooks because I wear glasses and the hooks are not very comfortable then, but I'm going to try anyway.
I recommend this IEMs because they may not be the better sounding on the market (I find them a bit bassy, and probably lacking some soundstage, but I haven't tested them enough and anyway it is of course a personal appreciation), but I don't think you can find anything better for that price. Mine were 14EUR shipping included...
Last but not least: the tips are "fine", so you won't be able to fit silicone tips from your "big" tip IEMs. For me that means I cannot longer use my favourite silicone tips, those that came with my old JVC Air Cushion. I can live with that, though.