Your decision that 150Mb will be sufficient for your needs was always going to be a personal, subjective one for you , if effect , only you could really answer the question you asked, others in different circumstances may ‘need’ more bandwidth and 150Mb would be limiting, personally I only have FTTC with 80Mb , but it’s sufficient for my needs.
As fas as some of the other points you raise , it’s actually a maximum 1/30 splitter ratio as that is Openreach policy and in practice, when you consider other physical limiting factors, like the number of CBTs that can be connected to a splitter (depending on the node size) plus take up is never 100% , in fact it’s on average less than a third of that , the chances of being on a splitter that is unable to satisfy demand at peak times is very small, however even in those extremely unlikely situations, the PON uses DBA ( dynamic bandwidth allocation ) to ensure the available bandwidth is distributed amongst the members of the network equitably, its not as simple as dividing the number of users ( up-to 30 ) by 2.5Gb , and allocating 83Mb each , there are minimums everyone will get , and the rest allocated ‘fairly’ up-to that customers profile limit, an example , if someone on a 1Gb connection is downloading constantly, others don’t ‘only’ get access to the remaining 1.5Gb , it’s much more sophisticated that that , and as ‘dynamic’ suggests allocation changes as the demand changes , but ultimately, it’s very unlikely that everyone will be making large demands at the same time .
