Trashy,
I have flown for two of the three locost airlines in the UK at the time, and I can say to you that it was fun, but hard work as well. I am not saying that Emirates is not, but at least you have for the moment a better quality of life here than flying for EZ or Ryanair. Go was the best time I had, great people to work with and more organized than EZY when I was there. I do not have first hand knowledge of RYR but it must be similar to EZY/GO so I am sure you will work your butt off. If you do go back to the UK and get in now you will get to do training etc, thus you will brake the monotony of flying 4 sector days with being in the sim as well. Maybe it is for you, maybe not. RYR does not have night stops, they do not have any other type than 737s so you will get to fly that for a long time..... Have you flown for locost carriers or is it your first attempt? Is this a move because you are fed up with the place or because your command has been put back. I have been here now for two years and I think there will be delays in command upgrades on the airbus fleet unless things change, but my decision to leave or stay would not be based on command prospects in the short term, but instead lifestyle, pay package family happiness in the long term.
I would look into BA or Virgin, but why do you want to go to RYR, why do you want to leave Emirates. Have you worked for RYR before, do you have inside info on the place? There are a few guys here for RYR and you can speak to them regarding their experience...