This is a strange place to ask that question but here goes.
Limited editions are unpredictable as to value and are based on the demand
for the work. The basic idea is that you want to limit the number of prints
to a value somewhat lower than you expect the demand. After the number of
prints sells out, presumably the value will increase as others wish to
obtain a print.
If you size an edition close to what it would normally sell, there is no
demand as you've saturated your market. People will generally buy because
they like the art or because they think it will appreciate. Your gallery
person evidently wants to hedge bets and opt for appreciation -- which is
entirely understandable. Hence the limited edition.
So, what's your demand -- how many do you normally sell.