In terms of my usage, I do a fair amount of landscape photography currently (both wet and dry conditions) as well as other nature but I also do some portraiture and sports. The monopod option that detaches from both would be utilized from time to time but again - they both offer this ability. Both come with a basic ball head and both extend to about the same height. I'm tall so it really doesn't matter - both are going to be a bit short but I'll deal with that.
After years of trial and error, I ended up getting one of each in my gear bag, and a separate monopod. FWIW, I'm not a fan of the tripods that have the detachable monopod. Monopods can be had on Craigslist/Ebay for very cheap. I got my Manfrotto monopod for $40 on Craigslist for track days. Get the right tool for the job, not a half-assed tool that kinda does everything OK.
Back to your primary question: I use my lightweight CF tripod for mobile portrait-studio/photobooth work due to its light weight, and my aluminum tripod for landscapes and startrails. Seems a bit backwards, I know, but the weight of the aluminum tripod just gives me a sturdier feel when setting up my camera, especially when it's for a 2 hr. exposure in the woods. When it comes to startrails/landscapes I want my tripod to hold my camera perfectly still; if it's at a cost of an extra couple of pounds, I'm happy with that.
Yes, the CF tripods do have a hanger hook for hanging your gearbag for extra ballast, but if you are putting your tripod in a wonky low-to-ground configuration, it may not be practical/feasible to place a massive gearbag directly underneath it. Now you're talking about packing an extra sand-bag just to hold down your CF tripod, and any weight benefit you paid for just went out the window. That's why aluminum solves all problems at once; heavy, and stable.
In my opinion, the cons to lighter-weight CF tripods (when used in the field) outweigh their benefits. Save up, get one of each. If you can only have one, go aluminum. Of course, YMMV.