I saw the ad in my new QST today...
It looks to me like they just slightly re-designed the front panel and went with a different RF module to get another 5w of rated power on UHF.
Is it worth it?? Not really. I'm waiting to see what the price will be on the 7900R, i have a feeling it will stay pretty level price-wise with the 7800R to stay competitive.
I have two 7800's, one in each mobile, i would buy another one without question, rock solid and reliable radio, don't bother waiting for the 7900R to release if your in a hurry to buy a radio now.
I see they also updated the following..
150R is now the 250R
170R is now the 270R
1800 is now the 1900
2800 is now the 2900, with an increase in power output to 75w on the new model.
Looks like they took their entire VHF/UHF line and just gave them a facelift and new model number, way to go Yaesu!! I approve of it, keep the overall costs low, make some minor improvements, and release another rock solid and affordable generation of radios. Some may argue that they are just selling the same radios over and over, but the way i look at it if there is no reason to fix something then just modernize the looks and sell them again!
The 7900R is the same except for the power button and knobs comparing it to my 7800's.