I'm using earphones for rehearsals and on stage and I recommend it. I have written an
article about my experiences that you probably will not understand, 'cause it's in Hungarian language.

The basics are: earphones are a combination of "earplugs" and "headphones". The earplugs protect your hearing and isolate from ambient sound/noise, and - at the same time - the headphones transfer nice controllable sound to your ears.
Important:
1. *Don't* use normal earphones (for mobile phones, etc.), they are not developed for stage musicians. Instead, use professional products like Shure
SCL3,
SCL5 or similar. Buy as good (= expensive) as you can afford. Personal opinion: I have SCL5, it is great, but quite expensive. I have tried SCL3 which was also very good.
2. The earphones *must* be inserted in your ears perfectly - else you will be disappointed. If inserted correctly they will/should sound better than anything you've tried before. Study this
animation for example.
3. Be careful and *don't* use the earphones on high level, as this will damage your hearing. Use the lowest volume that you can.
Pros:
- You won't hear disturbing noises, reverbs, low frequencies, too loud guitar amps or drumsets.
- You will hear much better sound quality, normal volume level, perfect ratio between instruments/tracks, and your part as loud as you want.
- You can move on stage without loosing what you hear (there are wired and wireless solutions).
- You can hear stereo sound, if needed.
- You can get rid of the bulky stage floor monitors.
Cons:
- You have to get used to wearing something inside (relatively deep) your ears.
- You have to get used to having extra wires/cables on yourself and taking care of them.
- If you are monitoring in stereo and you turn around on stage, what you hear will *not* follow the real positions: you will still hear the guitarist on the left but will see him on the right.

- You may need to use an extra microphone in the monitor mix for ambient noises (to be able to talk to each other with your bandmates, or to hear the crowd better).
- You probably will need a headphone amplifier or a small mixer on stage to transfer the monitor signal to your earphones. (Or you can make some tricks - changing internal signal routing - to use the OASYS' built-in headphone output.)
Hope it helps.