I cannot agree that the airlines will not want you. When this scheme was introduced I for one thought we are going to get some real no chancers in the right seat. I have to say apart from the one or two odd characters which has nothing to do with hours, only poor interviewers and selection, the standard is very good and the airlines know this. However if their is a shortage of first officers its more than likely that an experienced FO will get prefeference as you need a body of people to promote into the left hand seat either in the near future or in a year or so.
You could look at the problem the other way round;
How does sitting by a student for another say extra 450 hours make you a better airline pilot that a pilot who was specificallyl trained for airline flying even though he may only have around 250 hours