Buy both! Seriously, the small one would probably be more useful on your 618, however, you might get a bigger lathe someday, or a mill or whatever. Get what works for you best. Noga is definitely the right choice. They are amazingly nice, and change indicating from a chore into a pleasure. I had to use a cheap import stand today to help a friend with his lathe (fellow H-M member, hope he doesn't see this!). I had forgotten just how awful they are. A Noga will spoil you forever. Buy all the cheap junk you want, but splurge and buy yourself a Noga indicator stand. They are the absolute best and a joy to use, and no, I am not compensated by them... Anyway, you may need another indicator stand or holder for other uses. Again, choose Noga first. I recently came into a larger, old school, heavier duty Mitutoyo indicator stand, in new condition. It is the next best thing to a Noga i have used so far, and I am keeping it for heavier work. I gave away all my Chinese indicator stands, and the leftover parts from the broken ones as well, a long time ago.
