Ball Screw Lead

I have been looking for some ball nuts
that need to be:

1. Inexpensive
2. Fit into a 1.5" channel

I was looking to use either a 5/8" x .2" lead or 16mm x 5mm lead.
Technosiel has an ideal nut that would fit my needs. It is thier
KM Series Ball Nut. It is a cylindrical nut with an outside diameter
of 28mm. It is essientially a zero backlash nut and is only $63.73.

The problem is (there's allways a problem) they are out of stock on the
16mm x 5mm lead nut. Possibly until January, they are checking as I
type.
They may be able to get me a 16 x 2.5 or 16 x 10.

Anyone see any drawbacks to using one of these other leads?
Using the same 2:1 reduction, I could get twice the resolution but
lower speeds with the 2.5mm lead. I haven't worked out any actual speeds
yet.

I don't think I would want to use the higher lead, but what do I know?

Any input would be appreciated.

Mike Gann