Anyone with knowledge of M&K MX350/MX5000 Drivers?

Hi,

Just about to purchase a MX350 MkII, but had a few concerns and
wondered if anyone could help before I parted with my money...


Seller claims to haver replaced one of the drivers - the front facing one.
It looks like he has replaced it with a model number S30F77 which
correlates to the drivers installed in the MX5000 not the MX350 MkII
(as far as I can tell).

Will this have any adverse quality issues? or were they interchangeable?

Thanks