I would centralize "transaction" operations to one set of machines. Gopher, News, WWW, vote, logging, etc.. would all go on one box. This box must be able to deal with the performing the most intensive operation (likely news reading) at network rates.
The number of simultaneous transactions possible on this machine should be double the number of online users that are possible. Telnet users, and remote www/gopher access would make up for the difference.
If it is assumed to take 1 minute for a user to read a message (or discard it and move on), then this means a machine capable of providing read access on 10,000 entries per minute. With 8kb blocks, and given than most messages are smaller than a block, this translates into 80Mb/min, or 1.25Mb/s.
Clearly, disk hardware exists that can handle this rate, but this does not take into account the overhead of finding the right file to read. Theorectical ethernet rates being 1.2Mb/s, it is clear that ethernet would not keep up here.
Note that these numbers change little if one goes to a www/lynx type system and accesses the files in a client/server method. A user browsing menus requires the same data bandwidth as a user browsing news.