Reuven is better than Eisav, is Eisav our litmus test?

The Gemarah on 7B says that Leah called her first son Reuven, saying "See the difference between my son and my Father-in-law's son (Eisav)", because Eisav sold the Bechorah to Yaacov, yet he hated Yaacov for it, while Reuven had the Bechorah confiscated from him and transferred to Yosef, yet Reuven saved Yosef's life. The comparison between the two Bechorim is striking. In the words of R' Yaacoc of Lisa (the author of the Nesivos Hamishpat) on Chumash, the Nachalas Yaacov, "Ho wcan you seek a distinction between gold and excrement and filth, that we seek a distinction between Reuven and Eisav?! He asks other questions, including that "Reuven" only mentions the words Reu Ben, not the rest of the Gemarah's explanation?

The Nesivos answers that Leah said simply "Reu Ben", meaning look I have a son. She was always concerned, even after marrying Yaacov, that she should not fall to the Gorel, lot, of Eisav. Her concern was that she should not fall into the pattern of the earlier Avos that channelled their Zuhamah, their impurities, into their first children. Avrohom had Yishmael before he could have the Tzaddik Yitzchok, Yitzchok had Eisav before he had the perfect Yaacov. She was worried that Rachel was going to be the wife that provided sons - Zerah Yaacov- while Leah would be the recepticle for Zuhamah (just as Hagar was for Avrohom), having sons that would not be counted as Zerah Yaacov ( just as Eisav was not considered Titzcok's son). When Reuven was born it was immediately apparent that he was not Zuhamah by any means, just as it was immediately apparent upon Eisav's birth that he was Zuhamah, a Rasha. When Leah saw this she remarked, Reu Ben, see it is a son, a Zerah Yaacov, not like my Father-in-law's first born who was Zuhama; her fears were relieved.

The Nesivos explains that the rest of the statement of Leah's is actually the Gemarah's own addendum to Leah's comment, not her words at all, and the Nesivos goes on to explain the Gemarah to be dealing with a different issue; Aiyin Sham.

As an aside, there is a very interesting comment by the Chochmas Menoach on 6A on the Gemarah that says that a tefilah is only accepted in a Beis Hacaneses. He is Mechadaish that any Tefiloh one says outside of a B"HK, the next time the person Davens inside the BH"K, the previous Tefilos are acceped as well. He extends the same thing for Tefilos without Kavanah as well.