> Q's:
> 1. Is it ok to ugrade the server to v1.53 and leave the clients?

FB 1.5.2 clients must be fully compatible with FB 1.5.3 server

> 2. I'll be going go v2 when prudent to do so, any actions to take now
> or do differently when that time comes?

We support as much compatibility between old and new clients and servers
as possible. So i expect using 1.5.x\2.x clients with any 1.5.x \ 2.x server is OK.
If it is not so - it is a bug needs fixing. So far i not aware of such problems.

There are however some _documented_ incompatibilities\side effects in regards
of using different client and server versions :

a) local protocol is not compatible between 2.x server and older clients (i.e. before 2.0)
it must be not a problem at all as server installation includes right client library

b) changes in remote protocol in FB 2.1 can have some side network performance effect
if old client used with 2.1 server. This effects can be both negative and positive

Hope i answered on your Q's ;)

Regards,
Vlad