reciting a bracha in advance of a chiyuv

I was thinking about the custom of making havdalah on beer during the 9 days to avoid drinking wine and was wondering if there might be another solution to avoid that problem (assuming you think it is a problem and don't just drink wine, which is permitted l'tzorech mitzvah).  I don't have a copy of the Michtivei Torah of the Gerrer at home, but I saw in Yabi'a Omer (vol 6 33:6) that R' Ovadya quotes that the Imrei Emes writes that when his uncle, the Sifsei Tzadik, the Rebbe of Peltz, was an onein on Shabbos, he davened the motzei Shabbos maariv early and recited havdalah on a kos while it was still day outside.  Since an onein is patur from mitzvos except on Shabbos, had the Rebbe waited until motzei shabbos, he would have not been allowed to daven or drink wine.  By pushing up his maariv, he gained being able to daven and say havdalah. 

This is a chiddush gadol because I would have thought (and there are Achronim who indeed argue this point) you can't have your cake and eat it too -- you can't simultaneously ignore aninus because it's shabbos, but at the time daven a weekday maariv and say havdalah as if it's not shabbos.  

The Imrei Emes has another argument against this chiddush, and this is the point that R' Ovadya devotes his discussion to.  The Imrei Emes draws the following analogy: According to R"T (see Tos in Brachos 11), once you say bichas haTorah in the morning, you no longer have to recite a new bracha for 24 hours until the next morning of the next day.  If you said birchas haTorah Monday morning, for example, you don't need to recite a new bracha until daybreak on Tues.  What happens if you woke up before daybreak on Tues?  Even though according to R"T your learning at that point is still covered by yesterday's bichas haTorah, R"T will still allow you (so argues the I.E.) to recite a new birchas haTorah that will cover Tues going forward.  Says the Imrei Emes, when you recite that bracha, it's not because you have a new chiyuv at that moment, but rather it's because you can fulfill the new chiyuv of Tues in advance and in anticipation of at arriving.  So too, when Chazal allow a person to daven maariv early on Shabbos day and recite havdalah, it's not because those chiyuvim apply before nightfall, but rather it's because a person can fulfill those chiyvim in advance and anticipation of their being chal.  That's well and good if a person will indeed have those chiyuvim later on, but in the case of an onein who will be exempt, the trick doesn't work.

Ad kan that issue b'kitzur.

Nafka minah between these views should be whether you can say havdalah on wine before shabbos ends during the 9 days.  On the one hand, you could say that since it is shabbos you are still permitted to have wine, but on the other hand, you are using wine in anticipation of chol when it would not be allowed and so maybe it should not work.  

What about saying havdalah next shabbos before nightfall in advance of Tisha b'Av?  Would that work?  The Rishonim in fact debate this very point; BaHaG argues that this cannot be done (my son told me he plans to do a post on this BH"G, so see his blog later this week).  Is that machlokes parallel to the issue raised by the Sifsei Tzadik?  Or perhaps there is no comparison between a case where a person has a chiyuv havdalah, just cannot drink the wine, and an onein who has no chiyuv?