"Is it worth it in terms of Fuel economy?"
Based only on fuel economy, probably not. Don't expect to pick up much more than 10-15% or so on the highway. Around town, it won't make any difference.

"Is it that much easier on the engine because of reduced RPM's?"
Like the above, if anything, only on the highway. Easier on the engine, I guess somewhat, but redblocks can easily spin all day at 5000 rpm. Odds are pretty good you won't be doing that with OD or not.

"So whats the general feeling among all you guys who have much more experiance than I do??"
If you can pick up a working OD with driveshaft and crossmember for a couple hundred bucks, do it. You will not regret it.
If you find one that needs work, don't be surprised to spend many hundreds of dollars in repairs if you cannot do the work yourself. If you can do the work, it will be just hundreds!

The overall driving experience with OD is more rewarding on long hauls at highway speeds. Don't expect the car to be as quiet as a modern car though. It will be better and more relaxing on the driver and passengers than with the 4 speed.

If you are rarely above 50 mph don't bother with the OD gearbox.
--
'60 PV544, '68 220, '70 145, '86 745T