Any NSP that cannot allocate to you at least a /19 worth of networks
(IF YOU CAN JUSTIFY IT) is not worth using for an ISP who thinks they
need globally routable address space that they can advertise wherever
they want sometime in the near future. If you aren't going to get to
that point...what's the damn problem?
Except that if you give out /19s to newer ISPs with no allocation/use
track record, then the NIC may say "Sorry, you can't get more address
space, you haven't been efficiently using what you were given."