I have version-25dB.
When you play in rehearsal or concert, I put them systematically. Including when I go see a concert.

Most:
- Very linear attenuation, pleasant
- Easy to install / remove, this quickly
--25dB is good for all styles much noise as metal.
- Comfortable to wear, since molded to your ear.
- Discreet. The red dot on one of the two can quickly identify the right ear.

The -:
- Cher, necessarily, but essential if we want to hear his amp that is worth a fortune after 10 years of rehearsals.
- You feel a little in an aquarium in a bubble. The feeling is confusing at first, but after some use it can be done.
- Must be careful not to lose ...
Obviously, the attenuation is not completely linear, do not dream.
I get to analyze some things better than free, especially when the noise is intense.

I would do without this choice points. I paid mine € 140 I think, it makes good 2-3 years I have the boards. They have not yet bronchées I use them at least every week for rehearsal. For concerts, too, is indispensable.

Note that I'm a bass player, and that a notice would probably differ with instruments such as sax or singing.