Close the bottom of a sculpture?

[zazie]

When I started to do somewhat large bronzes the foundry closed the bottom and drilled 3 threaded holes to attach the sculpture to a base.

Now I am considering going to another foundry because it is closer but they do not close the bottom, instead they weld - as I understand it - two metal circles through which one may put "something" to attach the sculpture to a base. This foundry also charges more for this set up. The foundry says they always leave the bottom open.

I feel that an open base is an inferior product. Am I right or is it standard practice (or good practice forgotten)?

Would really appreciate your opinion.

Thanks.