We had a boat 20+ years ago with CNG, since then our boats have had propane. There is theoretically a little different heat value from the two fuels
but in practice they seem to cook about the same, like a gas stove
at home. The advantage of CNG is it''s lighter than air, so gas from a leak drifts up and out the normal ventilation openings. Propane is heavier than air so a leak pools low in the bilge and poses an explosion hazard. We have come to believe that a proper propane installation (which includes a sensor under the stove
with an alarm among other things) is adequately safe. The big negatives of CNG are storage and availability. CNG cannot be compressed into a liquid so it''s stored under high pressure in cylinders much like scuba tanks. An equivalent amount of fuel
takes much more space than propane. You exchange the empty cylinder for a full one and availability is a real issue. Check to see where you can do this around your normal cruising area, my sense is it''s getting harder to find. If you go far afield, it can be trouble.
If CNG availability turns out to be a problem, many stoves
(check with the manufacturer) can be re-jetted to burn propane. Often CNG installations have the tanks in a lazarette in the open, counting on the lighter-than-air for safety. To convert to propane you need a proper vapor tight locker, vented overboard. These can be bought as aftermarket kits and installed where the CNG tanks went.
I wouldn''t let the CNG issue deter you from the Sabre 34. If all else fails convert to propane.