more on eating vs. tasting - ta'anis, brachos, and meat during 9 days

Since I mentioned my wife’s sevara yesterday to distinguish te’ima (tasting) from achila (eating)as a basis for tasting fleishig food while preparing for shabbos during the 9 days, I owe a better follow up based on some comments (including hers!) The gemara (Berachos 14) poses the question of whether one who is fasting may taste food: is a kabbalas ta’anis the equivalent of accepting an issur achila, which does not include tasting, or is it the equivalent of accepting an issur hana’ah from food, which would prohibit tasting as well. The gemara concludes with a braysa that one who is fasting may taste, and one is also not required to recite a bracha on tasting (the shiur of taste is then defined as less than a revi’is). What is unclear from this simple statement is how it resolved the original question (see Tzla”ch). Is tasting permitted because a kabbalas ta’anis is a kabbalah only of an issur achila and not an issur hana’ah, or even hana’ah prohibited on a fast day, but a eating a small amount is not considered hana’ah? A number of issues may hinge on this question. 1) According to R’ Chananel (cited by Tos), tasting is permitted only if one spits out the food, yet Rashi (in Sefer haPardes) allows swallowing. If the prohibition on the fast or the mechayeiv of a bracha is hana’ah, then one might argue that swallowing even a small amount leads to hana’ah and tasting is allowed only if one spits out the food. But if a kabbalas ta’anis or the mechayeiv of bracha involves an act of achila, meaning ingesting a a specific shiur of food, swallowing less than that shiur would be permitted. Interestingly, the Rambam splits the psak: in Hil Ta’aniyos the Rambam prohibits swallowing even less than a shiur, yet in Hilchos Brachos the Rambam paskens that less than a shiur would not necessitate a bracha (this is how the GR”A paskens). One could learn that the Rambam paskened l’chumra on both issues to avoid a safeik, or one could create a more lomdish distinction between the mechayeiv of bracha vs. the kabbalas issur of ta’anis. For practical purposes, as my wife wrote, the Rama paskens this issue is a safeik bracha, and therefore achronim recommend to explicitly have in mind to have hana’ah when tasting to avoid the whole issue. 2) There is a major debate in Rishonim what type of ta’anis the gemara is speaking of. If the resolution of the gemara is that tasting is not considered hana’ah, that sevara might hold true on all fast days. But if the resolution is that kabbalas ta’anis only creates an issur achila and not hana’ah, on fast days which are obligatory m’divrei Torah (Yom Kippur) or divrei kabbalah, which have nothing to do with one’s personal kabbalas ta’anis, perhaps even tasting would be prohibited. 3) Classically, Yoreh De’ah issues depend on the shiur of ta’am, taste, as the threshold for many issues of bittul. Would one be allowed to taste a mixture to determine of there is a shiur of issur persent or not, on the assumption that tasting is not eating? (This idea may not work, as it may require a real ma’aseh achila to determine ta’am).
In short, considering that the issur achila of meat during the 9 days is a minhag, which is at best a din neder, one could argue that it depends on the extent of the kabbalah of the issur (like kabbalas ta'anis), and being only a minhag, perhaps one would have a right to rely on Rashi’s opinion that tasting even if one swallows is not prohibited. However, I still like my sevara better: toa'meha chaim zachu is an achilas mitzva and was never included in the issur of achilas basar. According to the logic of te'ima not being prohibited because it is not a ma'aseh achila, why should the heter only apply to food prepared for Shabbos? (And I guess the response may be that hachi nami, all te'ima is permitted, but who is cooking fleishigs during the 9 days except for Shabbos!)