Due to a tight squeeze between the floor and ceiling below, we installed a double sanitary tee (accommodating a toilet on one side and a shower on the other). Upon receiving the documentation for the toilet (Toto model MS854114S(G)/MS853113S) we discovered that they recommend against this and instead suggest use of a double combination wye (see page 2 of http://www.totousa.com/Portals/0/Pro..._MS853113S.pdf). Toto recommends wye in back-to-back toilet installations - which is not my situation as tee only serves one toilet and one shower.
Has anyone had a problem (or success) using a double sanitary tee in a situation like mine?