Re: 8 addresses, or 6?
"Plus trying to convince your upstream to route such a small slice"
I didn't realise it was even possible to get a /29 PI and expect it to be routed. Obviously it isn't impossible but if the routing tables fragment down to /29 then we will need some bigger routers!
It is much harder to aggregate lumps of IPv4 address space than it is to fragment it ever further. Think of the entropy. It will continue to fragment and each lump will become more and more "valuable" but IPv6 will take up some slack and eventually we will hit peak IPv4 value (I'm going to guess around 2020).
If you want a laugh, have a look at the huge numbers of address ranges on this and note how many bloody stupid little IPv6 ranges are also allocated: https://support.office.com/en-gb/article/Office-365-URLs-and-IP-address-ranges-8548a211-3fe7-47cb-abb1-355ea5aa88a2 I stupidly tried to use one of those lists to tighten up a firewall rule set and giggled hysterically as another address was accessed instead by a DC syncing to Azure Connect that was close but not one of the documented ones. MS are shit.