1. Whether the tri's have any advantage over standard plants depends entirely on your growing situation really. And also the particular plant. A heavy tri grown single cola will out perform a heavy bi, but a heavy bi will outperform a not so heavy tri. And once you top a tri, you have 3 growth tips instead fo the 2 from a bi. But if you start multi topping, then any advantage is lost really as you can get as many tops as you like from either. So ultimately, the answer has to be, because I can, or rather to be more precise, because I hoped I could but may not be able to , lol.
..... I consider phenotype and genetics to be one and the same thing, with the phenotype being the expression of the genetic code posessed. Of course I could be completely wrong there.