...If you're really going to be using it 90% at home, then the mobile is the clear choice....
To me, an HT's strength is being able to go with you on foot, by bike, or in a car where there's no room to mount a mobile.
I've found that if you have a decent antenna, you won't necessarily
need the power of the mobile. However, you always have the option. If you DON'T have a decent antenna, more power usually doesn't help much
...and since you don't need the portability of an HT, why would you limit yourself?
Now if you're going to switch back and forth often, then the HT has the clear advantage. The mobile and its connections is too clunky to move around.
I think the best option is to put the 7900R in your base station in the house, and save for one for your car.