short version of a long story, had a 2011 imac, bought an external 256gb thunderbolt SSD, the mac died. I cried. bought a 2017 one which has a fusion drive. so ive got this SSD that's brand new. I also have a brand new thunderbolt to USB adaptor but clearly that's no use so will go on ebay. however I can get a thunderbolt 3 to 1 adaptor for €50, and it says up to 10Gbps throughput. so im thinking, am I best to keep it, buy the adaptor, and use it either as my startup disc, though I guess the fusion drive wouldn't be much different speed, or for bootcamp as clearly that will be slower from the fusion drive as it just used the HDD bit. alternatively I could flog it for a loss on ebay, and buy a usb-c or thunderbolt 3, or even usb 3 SSD. but in real terms would any of them be better?