Well if you read my first statement in paragraph one you will see the clear answer to your question you pose. ,
Changing airlines as you say you have done, so I have to accept that you have done this without having to read and understand a post, sarcasm, then you should be able to discern that of course one can make a change for better. I was answering a direct question to a poster who had stated that he wanted advice and had posted his current position. It does not take a genius to figure out jumping from one airline to another can be a precarious event. So most old experienced lags like me I believe offer the same advice to a FO who is in the position he is. The present poor situation with the Max of course has impacts across the industry and may have halted FR command upgrades to lhs, this I am not privy to, but can say that with the normal amount of loss of four stripe bods it can't be long before a good level of opportunities will occur. To jump ship so as to speak to Jet2, given my recent understandings of upgrades, or lack of them, would be a gamble I personally, in that situation would not contemplate.
As we are aware the Max has put various Avaition companies into unknown territory, Jet2 being one of the most vulnerable as they have a number of old kites as well as now facing a potential bigger fish entering the "holiday" business, who has cash and clout to dent the present Yorkshire outfit. No one can see into the future, but one can use 30 plus years experience in my passion industry to say its going to get rough in the next 5-10 years unless you have vast amounts of cash and solid occupancy, two things that J2 don't presently have.
Anyone who undermines Easy and Ryan commercial models are seriously delusional.