Just remember that the results you may be getting using the HDSP9632 with Sonar for example on your system is not an indicator of how this card may perform on another system with another program.  But of course you have to work with what you have.
 
I am getting excellent results with this same card under Studio One on a Win 7 machine.  Plus the fact now we have the ability to set high output buffers with Dropout protection and low input buffers for super fast response means that all these things are possible under different circumstances.  And we also now have Low Latency monitoring added in.
 
The audio engine in the software also makes a difference.  I can loop over sections with total gapless performance with no CPU spikes while looped sections are repeating in large sessions with many synths playing at once.
 
I still have not tested the FF800 yet but will do so shortly.  It is also a great audio interface as well.
 
I also use the Midi IN/OUT on the HDSP9632 as an extra Midi port driving external hardware and it is also working super well too.  It has very low jitter on Studio One as well. 
 
Despite the fact this card is an older model it still works well even today and when the software changes the conditions under which it is operating then it too appears to go along with the changes and allow these new features to exist, rather well in fact.  It is interesting that what an audio interface can and cannot do can be tied to the software that it is connected to it rather than only doing its own internal thing.
 
Have you checked and updated the firmware.  I think you mentioned before you have. 

Occide, I run a 9632 PCI with Splat and it is rock solid.  There is a helpful RME user forum here:
 
https://www.forum.rme-audio.de/
 
Best,
 
Tom