I have no concerns about the pistons themselves, but their size and their fitment in cast iron 105+ mm cylinders. They (referring to the cast iron big bore cylinders) have proven themselves to be little more than 5-10k miles TBO (time before overhaul). Money would be much better spent on boring out a set of stock cylinders to 96 and matching a set of flat top keith blacks. Bump up the compression ratio and put in a good cam and you're golden. The 96 x 75 configuration will outlast the 103 or 105 x 75 configuration (or a 103 or 105 x 71) tenfold. Just my humble opinion. I know not everyone can spend the big bucks for Nickies, but there's no reason to build a time bomb if you're on a budget, since that's not good for the wallet either.
Charles Navarro
LN Engineering
http://www.LNengineering.com
Aircooled Precision Performance