What do you think determines the difference?

Well I bought the organs from a supermarket (if that counts) because I cant find any butcher store that sells cow organs here. They only have pig or chicken organs.

Yes, tallow is heated, though I have found that as little as 130 F is sufficient, and I'm hoping to get that down further with a rheostat. Some people apparently consider 130 F to be sufficiently raw, but Tyler does not and I want to see if even lower temps provide additional benefit. Heating and filtering works wonders in removing the strong taste from the suet. William has also reported this. I can't imagine just juicing it would have the same effect. In the longer run I plan on making a mix like Lex's, which should mask the taste of the suet. Have you tried mixing the suet with beef?

Was the suet you used grassfed or grain-finished? Was the source Slankers?

I ended up developing nausea after eating the room-temp cultured pastured pasteurized butter last night and found it pretty disgusting to eat, so that ends my experiment with that. The results were not as negative as in the past, so that does suggest I've had some GI healing, but they were still negative. I think I'll try making it into ghee to see if that makes any difference, since some people here and elsewhere have claimed that ghee doesn't trigger problems in people with sensitivities to casein and whey. Some day I'll probably try raw cultured butter too, because I found a local source of raw dairy that might have it--assuming they'll sell me a small test quantity. It's even more expensive, of course, so this will just be a scientific inquiry rather than a search for a practical food source.

I like the taste and mouth feel of heat-melted butter, but not the more solid room-temp butter (I find the mouth feel to be particularly unpleasant), whereas I prefer tallow in soft solid form over it's liquid form. If pastured cultured butter were cheaper and I didn't react negatively to it I would probably use it as a secondary or tertiary source of fat, probably in its heat-melted form, but there are just too many negatives in my case for me to use it.

OK, that could explain the different experiences. I don't get the well-being feeling from standard grainfed suet and meat and I find supermarket suet and even organic grain-finished suet also contains more connective tissue, brown bits and moisture than 100% grassfed that make the flavor of the suet even worse if I don't render it (and it makes poor tallow too).

Unfortunately, Lex just suggested that low-heating my suet to 130F may have a negative effect on its fatty acid bioavailability, so I may have to adjust what I'm doiing as well.