Welcome to the forum;
You didn't miss anything, it's a complicated question. But a good one.
The first Bear Series and Fireplace Series had no baffle provision. The revisions are by separate drawings of each part or new added part. One revision dated July 19 1977 adds a "Draft Box" and "Draft Box Baffle". These revisions are marked Grandma and Grandpa II. This was the first form of a baffle system. (There are revisions adding rear and bottom shields on the Fireplace Series designating them II as well. There is a note on those drawings stating "If the stove is installed on hearth in front of fireplace, vented into fireplace, shields are not required"). I don't have the redesigned Fireplace Series (III) prints for 1980, but the Smoke Shelf Baffle is shown in the 1980 owners manual.
Smoke Shelf Baffles were in the Fireplace Series III, Goldilocks, and Teddy Bear. The round plate across the flue was in the Honey Bear. The Insert only had a damper.
I have no revision showing any type baffle in the Bear Series from 1977.
These were all 6 inch compared to the 8 inch baffled stoves. So you have to take into consideration the stoves were made for larger 8 and 10 inch fireplace chimneys. That's what was existing, not 6 inch insulated high performance chimneys. Heat loss up the larger flues of the time was necessary, so a baffle added to make the Bear Series more efficient could cause rapid creosote formation. The worst publicity from customers would be a stove that works good, but loads up your chimney and burns your house down. So there's a fne line on how efficient one could be built.
Here's an ad showing the line for 1980 with the redesigned doors. Kinda cool seeing all the models together. The double doors would be baffled.
http://news.google.com/newspapers?i...=3330,8777721&dq=fisher+air+tight+stove&hl=en
From left, Baby, Mama, Papa, Goldilocks, Grandma , Grandpa, Insert. Not sure why the XL isn't shown. So far the ads I've found showing them are in Salt Lake City, Utah papers. The 'Sun' doors are marked with an embossed design the shape of Utah, and the serial number tag ends in UT. They were probably available by special order to other dealers. Time will tell if others appear made elsewhere. The first style with Sun doors had no baffle and have only been found with rear vent. The Fir Tree door style had a baffle. And was available in rear or top vent. It makes sense that the Fir Tree XL that matches the GM and GP III should be an XL III, but until I see a tag or paperwork on one, I won't speculate.
The IV was a glass Fireplace Series and Insert.
If there was a V, it was revisions in prints like the II, not on tags or advertised. (?)
The later Bear Series VI show no sign of a baffle system shown below.
I don't know the difference in heat output. The heat radiates noticeably more towards the front, so since the rear vent elbow is cooler, this heat being directed to the stove top has to make a difference. I heated with a baffled Goldilocks 24/7 for years with very little smoke. When I went to a Mama Bear this year, it smoked. My neighbors could tell the difference when I put the baffle in, and my neighbors aren't close. I didn't run it long enough this Fall without the baffle to notice output increase. My main reason for adding the baffle was after two nights of burning, the milk soured in the fridge 7 feet from the rear of the stove. My stove is in the middle of a large kitchen. Centralized in the house. The heat emitting from the rear elbow radiated towards the fridge, and the baffle directs it to the stove top. An Ecofan helps blow it forward. That's a lot of heat not going up the chimney. No creosote problem, so it was all wasted heat going up. I was surprised at the drastic reduction in smoke. If you're burning the smoke in the stove, you have to be getting the extra heat out of it.