Can't wait for the updated Mac Mini, if it ever ships, so will go to a new 27" iMac. Those with just a HD or fusion HD are easily available and often on sale, unlike the SSD models. Wondering then if an Thunderbolt 3 connected external SSD would be as fast or nearly so as an internal SSD, and if cost effective. If so, can it be just a standard SSD in a Thunderbolt enclosure or is there a special T3 SSD?