I have no idea how big mine are, they are all underneath my undergravel filter and I never see them (I saw a 2mm baby one like 3 weeks ago).
For all I know they could be massive!
The only other MTS I see are my spiketails, the mother whose 1.5cm, and the babies are 3mm at the largest.
A 1 inch MTS I've heard of, but never seen.
I guess they are just slow growers? Would be interesting about the colour variations, there's quite a few out there.