Tenants vacating 60 days before lease is up

[NA Jones]

I have clients who are closing on their home in 10 days.  Their lease isn't up until April 30th.  They wanted a later closing date, but when it came down to it, they wanted the house more :)

They are prepared (and legally obligated) to pay both rent and their mortgage for April.  I have the feeling they'll be moved into their new home by the end of February.  

Is there any chance they could negotiate handing over the keys much earlier than April 30th in exchange for a partial discount on the months rent?  Give the PM 45-60 days head start at getting the place rent ready in exchange for a 25% or so discount on what are obligated to pay?  Would that be attractive to the landlord at all?

They are in a large apartment complex with a property management company.  I'm sure this lessens the chances greatly.  But is there a chance?