Well ... that's a toughy.
Kydex usually grabs the gun in a few select locations, wears the finish a little and it goes no further. Leather tends to touch the gun in every location, the wear won't be as pronounced in any one location but it continually, slowly wears everywhere.
What you CAN do is make sure if you go Kydex, don't go hard plastic as in uncle Mike or some of the other cheap ones. We all use the word "kydex" in a general way on these forums but if you are serious about wear select a one of the custom makers of REAL kydex.
BearClaw Holsters
http://www.bearclawholsters.com
Dan Hillsman
http://www.hillsmanholster.com
Others ...
For Leather, I've found that Mitch Rosen, Alessi, and a few others hug the gun VERY tight ... which is good in some ways but if you are worried about wear, specifically ask for one that fits a little less snug ... maybe some of the other guys here can suggest a leather maker that balances retention with presention ... some are just too heavy on retention.
Lastly ... I have Kimber Tac Pro and it's finish is a bit on the wimpy side. I think the Eclipse has a better quality finish and you might not have anything to worry about, anyway.
My .02. Enjoy the Eclipse and shoot safe.