CPF has lots of reviews and beamshots of the TVNC/OpticsHQ 6P drop-in and the E2 conversion head. There are also plenty of reviews and beamshots of the Malkoff products.
To find the TNC E2C adapter, go to the TNC Products web site, click on the "
TnC, Aleph & E Series compatible" link in the "Categories" box on the left side of the page, and select the E2C finish of your choice.
A Malkoff M60's advertised lumens is higher than the figures cited for the TVNC. Presumably, however, these TVNC figures are for their 6P drop-in, not their TX2 E2 conversion head.
Regardless, I doubt that the lumens differences have much real-world relevance. More meaningful are any differences in beam pattern, which might tip the scale for one product or the other.
I have the OpticsHQ version of the TVNC 6P drop-in and the beam pattern is quite nice. Bright hot spot, nice spill, negligible Cree rings. Works great with their multi-function tailcap, but that is strictly a 6P-family tailcap, not an E-series compatible product. I also have a Malkoff M30 and I don't see any compelling beam pattern features that would make me definitively pick one drop-in over the other.
The E2C approach will give you a bezel the size of a regular SureFire 6P -- large in comparison to an E-series light. The TVNC E2 conversion head is only a littler larger than a KL4 head.
You can buy bare 6P bezels from any number of sources on the web. Use Google. The CPF Marketplace also has frequent ads for bezels for sale.
Personally, I prefer the E2 conversion head over the E2C/6P bezel approach. I favor the more compact size of the E2 conversion head. IMO, if I want to have a 6P bezel, I may as well also have a 6P tube.
The E2C/6P bezel approach has its merits, though. It offers the flexibility to use whatever 6P-compatible drop-in comes along, as LED technology advances. With the E2 conversion head, there isn't much of an upgrade path short of mod'ing the head.