I've not been able to tell a difference in edge retention between the two and I've not had any rust issues. I'm not sure how I would choose between the two, I have several, they're so light and inexpensive I have a hard time passing em up. So I guess I would suggest buying both and see what you like best.
I think DaKruiser hit it on the head. I don't think you will see much if any difference in the edge retention.
As for a specific model I have an older "Tri-Flex" with the black hard plastic handle and I have one of the Companion MG models. I don't know if they do the "Tri-Flex anymore, but it is similar to the #760 Craftsman. I like the softer handle of the Companion because it is more grippy, but I really like the Tri-Flex too. They both came very sharp and have held their edges well. Both of mine are carbon steel, but that's just because that's what they had when I was in the shop. I did grind the spine of the blade, out towards the tip, so that it had nice square corners to it, so I could use it with the fire steel.
I did see that they came out with a newer "Companion Heavy-Duty" which has a thicker blade. I would like to get one of those to try out.
On Feb 9-10 Brad will be sat up at the Lafayette gun & knife show at the fairgrounds. He will have my Mora knives on display. Some are stainless and some are carbon. I have about 8 different models to choose from.
Just an FYI.
The carbon steel is going to be easier to sharpen with improvised abrasives. I think they take an inherently sharper edge as well and are definitely more forgiving of what sort of abrasive you use.
i have the carbon "swedish military" one with the green and black handle. I'm a big fan. I will probably get one of the stainless ones in the future too.
Spring is coming, and the panfish are soon to nest. You guys should pick up their bad ass filet knife Its held a better edge than anything else I've used. I'd really like to try out the Helle on this year.
Ooh, the Helle's are supposed to be some good knives. I keep thinking about trying one out too (darn that need for money and all the non-fun places it seems to go first). If you do get one, please post a report on it.
I bought a Helle 7" filet blade and used a new cork Fly rod grip for a handle. It is sharper than a Sicillian Barmaid and the blade is a little stiffer than most US filet blades, which I like. Oh, and it floats blade down with the cork handle.