@Pjotr I don't have much experience with Tallow use in soaps/creams, however, from what I understand it adds to the "Creaminess" of the lather. See essentially, soaps are made up of different oils, butters and sometimes fats (like tallow, Lard, etc).
All of my products are currently Vegan ie. do not use any products from animals. I may dabble with a tallow based soap in the future. I own a few that are tallow based, however, I have no preference over one or the other. Personally I look for 2 things in a soap/cream. That is 1) Performance 2) Scent. But thats just my personal take on the matter.
I hope I've at least answered one of your questions. I'm not too sure about the yellow discolour when using tallow in soaps, although I would assume that it may be the case.
@Nonick Heard you loud and clear. I have some "Sample" pots on the way, so I aim to make some sampler packs that will contain each of my soft soaps as well as some of the glycerine based soap.
Initial feedback I've had on the Glycerin is that it's fantastic performance, however, the opening to the soap is too small. So thats why the discounted price. I aim to increase the cost slightly when the new tins are used.
Feedback on the soft soap is that performance is top notch with a nice face feel after the final rinse. The only complaint has been that the scent could have been a little stronger (which I am working on next batch). This is the honest feedback I have received so far. The only way I can excel is by listening to my customers.