Downside of using one transport for only one producer/consumer?

Hi, I am using one transport for one producer/consumer for some of the scalability reasons on my server side and I want to stick to that.

It is mentioned in some topics that it is better to have all producers on single transport because bandwidth estimation is better in that case and I think same goes for consumers as well.

I want to ask if there is any downsides to using one transport for one producer/consumer? If yes then how much difference in bandwidth estimation, performance in percentage it will have with the other approach (one transport for multiple producers/consumers) like 5-10%?