I'd be interested in learning more about this, if you don't mind. Which one did you get first? Why did you choose to get the other, after the purchase of the first? Size only (although you can do a 5 gal batch in the CF10)? Pros and cons of each? If you had to choose only one, which one would you choose?
I keep flipping between the Flex+ and the CF5. Price matters, of course, but so does functionality. Although I'm not sure I'd get full benefits of all of the functionality of the CF5. Maybe I'm wrong though.
I bought the Flex+ first. Spike had a Black Friday sale at the time, so I went with it over the CF5 (which was what I really wanted). At the time I was willing to pay a little more for the CF5, but impulse got the better of me. I don't regret my purchase as it's a great fermenter.
The CF10 I sprung for later. The main purpose was to use it for my 10 gallon batches so I could keep two of my Fermonster carboys open for two 5 gallon batches. I got to really hating using two of my four carboys for a 10 gallon batch. It's nice to have one vessel for those batches now.
Pros/Cons of each?
Flex+ is a great purchase for the price. Love that all the ports are welded triclamps. You can also do pressurized fermentations in it and it also has a lot of accessories for it like their conicals. The main con that I see is no dump valve for harvesting yeast. I plan on getting a yeast brink, so that might make the CFs that much more appealing vs the Flex/Flex+
CF10 biggest pro for me is fermenting a much larger batch in one vessel vs splitting it to two smaller ones. It also has the ability to do trub dumps/yeast harvesting. The main con is price. I say that lightly as I do think it's a pretty great conical for the money. When you add on all the other accessories though, then the cost goes up. I look at Spike's conicals, or any brand conical for that matter, much like kegging. Kegs average about $45-$55 dollars used, but you have to also figure in cost of co2, kegerator/keezer buy or builds, taps, etc. There's an upfront cost, but once that's made they are really worth their money, imo.
So which would I choose, the CF10 or the Flex+ if I could only have one? Easy, the CF10. It's just more flexible (for lack of a better word) than the Flex+. I would choose the CF5 over the Flex+ as well if that's what you're looking at.
I know I could do 5 gallon batches in the CF10, but to be honest, doing half batches in that is like never burying the throttle on that suped up hot rod you just bought.
On another note. The CF conicals do
not come with a racking arm, even though the Flexes do. IMO, if you go with the CF, I would highly recommend the racking arm, casters, and bracing shelf. These things are heavy when full of wort. I added those (along with the extension legs) to mine and don't regret it. Hope this helps.