I've never used a 736r, so I can't compare, but I presently have an 847. It is an excellent satellite rig but not nearly as good as my TS-690s was on HF, (I chase DX) However I've been learning to adapt and still bagging new ones. Plus the extra 50 watts on 6m is nice. I also found it is not nearly as user friendly with my MFJ external tuner... I have to adjust power on the rig before hitting the tune button on the tuner. With my kenwood, it was one button tuning right on the rig.
Some of it's quirks... it is prone to having problems with the power switch going out. Mine has lost the 'catch' and won't stay closed, others have had the contacts burn out. I have mine 'jumpered' in behind the switch and I turn power on and off at the supply. Some have an issue of low headphone volume, but that mostly is because it's designed for low impedance headphones, not the 32 ohms ones commonly available today. If you plan
to use computer control the very earliest models did not have
bi-directional serial ports, but that can be checked by the serial
number... I believe it's a small number of rigs. Google is your friend
for information on that. =^)
For satellite, the named sat memories are nice and it has built in preamps or it can power remote preamps. The extra filters are a little hard to come by and can be expensive.I've only acquired a CW filter. Their are no birdies that I am aware of. The rig was designed for satellite and that remains it's forte. I had both rigs on my bench until my 690 developed a problem. Once I got used to the 847 on HF, it was nice not to have to switch my key back and forth or have two sets of headphones. What I am saying is, if you want a great sat rig and an adequate HF rig, it is a fine choice. But if HF is your primary goal and satellite is an after thought, keep your 736 and get another HF rig.
Prices run $800 to $1000 for a used 847. I paid $1000 for mine on a local purchase in very nice condition and sold the external speaker that came with it. Prices have dropped in the last year or so and I wouldn't pay more than $900 shipped unless it had the FC-20 external tuner with it. They can be found for $800, but consider the condition. These rigs are coming up on 20 years and many parts are reaching the point of becoming unobtainium. - Bottom line though... outside of a IC-910 or 9100, it's probably the best satellite rig you can own. (personally, I like the layout better than the 910/9100s) If I had the money, I'd buy a spare.
As always... your mileage may vary, batteries not included, no warranties expressed or implied. =^D
73, Kevin N4UFO
"Control is the need of the fearful mind. Trust is the need of the courageous heart."