New or used cartridge


I have have good experiences buying a previously owned cart in the past, but have heard several telling me to buy new..  I wish there was a way, to tell how many hours was on a used cart.  Other than putting the cantilever under a microscope,  I see no way concerning the hours/use/condition of a used cart..  I kinda look at it as buying a used car.  Let someone else take the initial "hit". then buy from them, as they're moving over or up.  I have an excellent Koetsu Urushi Black I'm going to put up for sale.  I love it's sound, but am wanting to move up the ladder so to speak.
Please give me opinions concerning this.
handymann
@mulveling 

I've also heard that Koetsu will not touch a cartridge that's been worked on by any 3rd party.

Not only Koetsu, but almost every respected manufacturer will not touch the cartridge if it was refurbished by somebody else before. 
About SUT’s - why not DIY? You can get raw transformers from Lundahl from K&K Audio that are out of the park. I use a pair of silver 1931Ag; less than $2k. Cartridges wear out - SUT's, not so much.
Yes, Lundahls though K&K are a great deal (plus very small fee an assembled box); in my system I prefer the Sky to the copper LL1931, but I would absolutely love to hear the silver-wired LL1931Ag or LL1933Ag (or their higher gain versions) sometime. The LL1931 is certainly a great value for the money. Very transparent, airy, and detailed; a refined and grainless sound with an awesomely huge soundstage. The Skys give up a little on those things, but in return supply more body, warmth, and bass impact. I wonder how much of that sonic difference is attributed to the amorphous core (i.e. would the laminated metal core LL1933 sound closer to the Sky?). In my opinion the Sky makes the Koetsu sound even more "Koetsu", but it’s valid that some would like to take it in the other direction. The Skys are also slightly smoother and more refined than the older 1131 CineMag.

I agree that acquiring a great SUT is a good investment that will never wear out.
@terry9
Dang man, unfortunately I’m on the opposite end here in Atlanta, and travel doesn’t agree with me. I’ve already come VERY close to blind ordering some of these silver-wired Lundhals before, and may end up doing so in the not-too-distant future. I guess if I were going to pick a horse right now, it would be the LL1943Ag, for the higher gain and traditional laminated core.

I already run & love pure silver for all my system cabling, and I’ve read that silver wiring in transformers makes an even bigger difference than it does for other wiring applications. Hence my strong interest in these LL's