Both XM and Sirius have terrestrial repeaters in Syracuse so this helps the signal downtown and indoors. They really help out the portable units so they might just work out for you.
Minus the repeaters, Sirius' signal generally fairs better the further north you go. XM's satellites are parked above the Equator while Sirius' satellites float overtop of North America. This means that they're much higher above the horizon allowing the signal to get over top of more objects. You go much further north, even a semitruck parked next to you is high enough to block XM's signal. Some will say that XM's signal penetrates trees better (as at times it can be a bit stronger) but since Sirius is higher in the sky, less things block the signal.... unless you're indoors.
Indoor reception in areas without repeaters usually requires the antenna to be outdoors for best reception although many get good reception near windows.
The new Sirius Stiletto 100 portable unit has WiFi built into it so if you're indoors and can't get a good signal, it can stream the Sirius channels over the internet via WiFi. No XM receivers have this capability.
I find that Sirius radios have very similar reception as although the facade may look different, most modern ones have the same guts to them receiver wise. The main difference is in antennas. Some are better than others. The SIR6 is the best home antenna, and most say the round flat Sirius antenna is the best car antenna.
I drive all over with my Sirius and I get a good signal 99.9% of the times. There are drop outs parked underneath overpasses or gas bar overhangs or really heavily treed canopied roads. I find its well worth the money and enjoy every minute of it.