if client is made correctly, there is no harm using many relays
however, it is possible that client is coded badly, and it crashes the whole thing, or just uses all your cpu and network, while it tries to query all the relays at the same time
how i would implement this:
- allow user add any number of relays
- add additional setting n for how many relays are actively used
- client would randomly select n number relays from all relays each time it connects to relays