Probably, the variant on 32 channels will be more interesting.
Pay attention to the sizes of prisms.
At the big length of a prism you cannot supervise a direct beam welded seams on 10ìì and with small radius.
Probably, for a thickness 10ìì it is required more 5ÌÃö, (but the price...)
Necessity in phase frray on 64-128 elements depends on objects of the control.
Necessity of the scanner depends on objects of the control.
As the encoder on badly prepared surface to work not conveniently.
See alternative offers (comparing the price).