Really depends on the airline in question. Especially larger ones have contracts with pilot schools, quite a few prefer MPLs as they are trained on their procedures from day one. Others are happy to take on pilots from different schools, but only take those that did an integrated course in one of the big schools. Others don't mind how and where you did your license, as long as you have it and pass their assessment process. And there is always a certain percentage which will have a very hard time finding a job at larger (and usually that equates to better conditions) airlines. Which does make the point for passing the selection before you sink around 100k in a fast expiring training.
Of course there are other employers out there, but not really all that many in Europe.