I presume you had to turn off the RS10 at the mains if it wouldn't respond to the remote? If so did it work again once you'd turned it back on (might be better to wait 30 minutes before powering it back on to left the lamp cool fully)?
Re the HD350 verses the HD750 debate I understood there was a difference in terms of hardware (makes sense as the CMS requires some processing and therefore a chip or two to do this). Some manufacturers will use the same PCB for different models, but only put the components in for the appropriate model (I've seen PCBs with 'missing' components before when I've taken the case off other equipment). I've never opened my HD350 so I don't know if this is the case here though. At the least there is the better (selected?) panels/improved light engine in the HD750 as the CR was claimed to be 20,000:1 higher, some would pay the extra just for that difference (not unlike RS35 owners do these days).
FWIW I went with the HD350 as a home demo at the time showed my room was more of a limit and I couldn't see the value in the dearer option. Nowadays I've improved my room and also bought a (beta) VideoEQ Pro so I may have been better getting that HD750 from the start, though it still would have cost me more in the UK to do this, but I would have had better CR also.
Zooming: Been there, done that, bought the lens...