Fleet chnage is nothing you can do. A friend of mine joined as FO on A320 and less than 2 years later went to 350. If you re planning to join, try to enjoy life as a pilot living in Doha. Fear culture is more at Cabin crew side than us. Flight deck environment is good and I never had any problem so far. The Training department is way more bearable than EK. Bidding system works well for me and I can commute back home almost every month.
If coming here with high hope of quick upgrade or widebody fleet, you may end up disappointed. Yearly increment is not consistent, dont always expect that. Doha is not super fancy like Dubai but there is plenty to do nowaday. Night life is fun if you know the place (there are so many).
If the aim is money and experience, then you should be fine. Having my family stay back home, combining extra from housing with kids education (oversea), I earn and save more than many friends. You can be happy anywhere if you know what you are doing.