HD-SDI is an option Orri and I discussed
The reason we disregarded it was due to addition of more processing in the signal path - both at catalyst end (scan converter or Blackmagic Device) and the SDI processsing in the projector. This could lead to increased latency. Also 1400x1050 is not a supported HD-SDI resolution. Technically 100m is on the limit of HD-SDI. The cable would probably cost more then the processing!...
100m DVI fibre, which appears 'transparent' to mac, supports any resolutions up to 1920x1200
Slightly more expensive - but can bypass the projector processing and provide lossless native resolution.
Simon