The reason it worked for the SiriusBackstage original poster is because his local channels don't interfere with the band-stacked feed for 110 (or 119, 118.75, 121, 105, 61.5, etc.)
This is why the "check switch" fails for him but it appears to work otherwise if he ignores the "check switch." This arrangement is totally YMMV and is Not Supposed to Be This Way.
The band-stacked feeds can interfere with local OTA channels.
The lower part of the band-stacked spectrum overlaps with TV's UHF band, hence it may or may not work for you.
It happens also to be one of the patents that E* is being sued for--the band-stacking of left/right polarity into one big block of spectrum to eliminate any need of switching the polarity.
With the risk of overloading the current of the LNA inside the XM/Sirius antennas (which expect 5 volts and not 14/17 volts) I would stay away from any diplexed arrangement with XM/Sirius.
More worrisome, the XM/Sirius signals are at the very top of the design spec of most run-of-the-mill RG-6 cables, at around 2.3 GHz, and they lose signal dramatically on anything but RG-147 cable, and even those 22-foot-long RG-147 cables still need the amp inside the XM/Sirius antenna in order to get any kind of signal to the receiver at all.