>> max. number of connections latest releases of Firebird can handle ?

There is no built-in limit in the engine. Only practical one - amount
of memory.

> SuperServer has hardcoded limit in 1024 connections. Other
> architectures are limited by OS TCP/IP stack. To get more you must use
> clustering.

This is not true. I've established 5000 conections using XNET and 64-bit
build of Firebird. INET have internal limit of 1024 sockets, yes, but
this is not engine's limit. WNET limited by 255 pipe instances. XNET
have no limit.

Note, 32-bit build of FB SS on windows will reach its limit of 2GB of
virtual address space near after 840 connections.

Regards,
Vlad