Well, if given a choice  I  would go for one of the newer in-boom furlers.  Better sail shape, battens, less consequence in jamming, etc.  The systems are so much better than they were in the past ...
IMHO,  YMMV...

Converted to in mast in 08 and without a doubt the BEST INVESTMENT  made in the boat. Yes the sail is cut flatter and with a negative roach as compared to a slab reefing main but still powers the boat fine. Yes when I replaced my 135 I went up to a 140 with foam luff to make up for sail area loss in the main but my boat kicks but.  Consistently out performs many slab reefing mains, could be the sailor or max prop but still fine performance. As for in the boom TURN 180 DEGREES AND RUN THE OTHER WAY.  What are you gaining a good sail retention system, you still have to hoist it 44 feet each time you use it.  If considering in boom go with a Mack pack sail retention system and slab reefing main. Add a tides track system and you have a doable system. I work for Mack Sails and rigging and we sell all but for me in mat was the only way to go. We sail frequently and see many boats out with jib only, we have never sailed that way in 6 years.  As my wife says, "the furling main even if unbattened, is much faster than a sail cover". As for jamming hasn't done it in 6 seasons, learn the right way and o it that way and you'll be good to go. 

Chic Lasser
Past Commodore c36ia

I have had in-mast furling for the last 4 years, and its terrific. It would be hard to return to old style mainsail handling. We can hoist and lower the  mainsail in less than 30 seconds, all from the safety of the cockpit.

And its so easy, even my 50kg wife can do it!
 

If you are considering converting the boat that you have I would think that going to "in boom" would be a much simpler conversion. I have in boom and I would never go back. We have a "winch buddy" for hoisting and it is literally effortless. Same with reefing. There is no more debating on when to reef, just do it. It takes about 20 seconds.

Cheers,

It's funny, I often hear, from Catalina 36 owners (who don't have in mast furling) about how they have heard from other sailors that in mast mainsails jam and cause problems. My wife and I have owned our 36 for over five years now and have yet to experience a problem with the in mast furliner. I agree with Chic, if you are conscience about how you treat the furling of your mainsail you will never have problems. Yes, I know there is a trade off of performance, but you more than make it up in safety. That's my two cents.  

Not a chance I would go back to a hoisted main - Simplicity.
 

This may be a bit of a late reply, but if you haven't made the decision yet, here's my 2 cents.  I bought my C36 about 6 months ago.  She's in great shape, and the only thing I was worried about was the in mast furling main.  My concern was based on the common notion that furling sails are less productive and can jam and be a pain in the ass. 
I had a slight learning curve - rather than haul or drop into the wind, turn the boat a few degrees leward and loosen your mainsheet.  The way the sail rolls in and out isn't in a straight line aft - it's off to port.  When hauling, release the vang.  When dropping, tighten the vang. 
Now that I've spent time with this system, I have to say, I'd never go back.  I like to single hand, and often have non sailors on my boat.  It's so easy and SAFE to haul, drop or reef my main. 
Re power: You have to learn to get the most efficient shape out of a furling main, but you can get good performance.  I was cruising at 7.4kts in 15kts wind on a trip last summer.  Not too shabby.
 

Oh furling mast, how I love thee.  Let me count the ways. 

1. zero effort to set the sail
2. zero effort to stow the sail
3. loosen the out-haul to get a great shape down wind
4. Reef without leaving the cockpit - overnight in building winds, it was so nice to safely reef
5. It's so easy my guests can deploy it
6. I will never fall off the boat and die reefing my main

Did I miss something? :)