Bought a couple of pairs and had them fitted to existing bb cups (Shimano & Raceface) but both feel really really stiff(before i fitted to bike), to the extent that i removed the bb and fitted my old Hope bb instead which spins nice and freely

Do they need to bed in and loosen up or has the mechanic (that i trust to do a proper job) ballsed up the install when pressing them into my cups?

Probably just the better seals are a bit stiff and need to bed in. As long as the inner race turns smoothly it should be ok. If it feels lumpy, balls up alert!

Thanks. It does'nt feel lumpy, just a huge amount of friction on inner race which is worrying.

I'm right in thinking that any sealed bearing can be damaged if pressed in poorly?

Potentially, depends if it was pressed or hammered i guess…..