I am looking to pick up two M600 weapon lights for two rifles I have and would like to pick up the old M600U model over the M600DF model. Unfortunately, this light is listed as discontinued on all the dealers' websites that I can find. The light, however, is still listed as in stock on Surefire's website albeit for a high markup compared to what these lights used to sell for through a dealer.

Does anyone know if the M600U is being discontinued? It is not currently listed as a discontinued model on Surefire's website, but it seems to be heading that way.

In the event that I cannot find an M600U for a decent price, may anyone recommend a better light with equivalent specs from another company? I looked at some of Streamlight's offerings and was not impressed. Does anyone here prefer the M600DF over the M600U?

It's discontinued, but only due to the legacy body style. The same light is still available as the Pro with the swiveling pic/mlok mounts.

The Pro version of the same light

The legacy bodies are still available at vendors as a replacement part.

Legacy body

Body at Primary Arms

Edited to add links.

Thank you for the information. So you are saying I can buy the body and the head separately to put the light together? do you know of any vendors that are selling the KE2-B head by itself?

Somewhat relatedly, what is the difference between the KE2-B and KE2-A head?

No, I meant that you could buy the Pro and if you really wanted the legacy type body, just buy it separately. You could also likely sell the Pro body and mounts for more than the price of a legacy body.

That said, you could piece one together, but one can buy a complete light for not much more than a head. B&H Video sells everything separately, including the KE2-B heads...
https://www.bhphotovideo.com/c/product/1451235-REG/surefire_ke2_b_bk_ke2_1000_lumen_led_conversion.html

The A head is the discontinued 500 lumen legacy head. The B head is the current 1000 lumen head.

I'm on the lookout for a new black KE2-A head as I have a bit of a collection going.

I forgot to add: as to alternatives from your OP, if you want to stick with 123 batteries, look at Arisaka bodies and Malkoff heads. Both of which are available from Arisaka. Malkoff just sells the heads direct, not weapon light bodies. Also, this may be useful...

https://arisakadefense.com/blog/arisaka-modlite-and-surefire-beam-shots/

Thanks for all the information. I decided to go ahead and buy a full M600U unit in tan and a KE2-B Head in black both from Surefire. I'll pick up a black, Legacy body and tailpiece from Primary Arms.

I don't know way they would discontinue the Legacy body. Its simple and idiot-proof: I'd bet enough people would prefer the use of CR123 only and not want the strange 640 swivel body to warrent their not discuntinuing it but what do I know.

I can't believe it either considering their legacy mount became the basis for an entire ecosystem of bodies from many manufacturers like Arisaka, Modlite, Cloud Defensive, etc, and of mounts of all types from too many companies to list. Seems shockingly dumb to discontinue.

That said, I was a legacy hold out, but finally tried the Pro and it has the benefit of an extremely compact mount. I like both types, but I'm a collector that likes variety.