Not sure......my occasional passenger prefers the tourpak. I think because it is taller and has a little more padding higher up the back. Never asked if it gave more room though.
Momma prefers the TP. There is definately more space for the passenger with the tourpack. The TP also has a few different positions you can put it at. I can't remember the last time I had the sissy bar on.
I have the standard height passenger backrest and my wife would prefer the tourpack. Not sure if theres any more room with the TP but she says its way more comfortable.
Can't say about the space. GF says she hardly ever sits back into the backrest. Have the tourpak also but since it was a Christmas present we haven't ridden with it on. They are both QD so when it's a trip it's the tp when it's just riding it will be the bar and backrest and when it's just me , well even the windshield comes off. Best of 3 worlds