I can't comment on the Mini Manix, as there aren't any stores near me to actually try one. I did however FINALLY take delivery of my full-sized Manix this weekend (ordered it over two weeks ago), and can give you my impressions of it.
As a background, my Spyderco knives are a serrated Clipit and a Native III plain edge. I've been carrying the Native for the last year or so, and really like it a lot. It is a little small, and I really like flat ground knives. The Manix seemed like a good solution to this dilemma.
When I got my new Manix, I was awed by the sheer size of it! I'd read other posts about it's size, but it wasn't until I held it in my hand that I realized how really almost over-sized this knife is. It really fills my hand, and is almost a little cumbersome to pull out, slide my hand down to the hole, and open. Also, I realized my new-found sharpening skills were still a bit lacking -- my Manix had hairs falling off my arm by just barely brushing the hair.
This knife feels good in my hand, though the flat handle and rather sharp G10 isn't the easiest to get comfortable with. I really like the so-called 3D effect on my Native, and still carry it (though the Manix definitely goes along, clipped outta sight for the ride). So far I've torture tested my Manix by furiously slicing some aggressive tomatos, and a cucumber that was giving me some attitude. I'm happy to report that the Manix easily handled them both! Oh yeah -- I also did the paper slicing thing, like Sal does in his Sharpmaker video, just because I could.
I think you'll end up really liking your Manix. I personally always carry my RAT-7 D2 in the woods, but that's because I like to chop a lot, and just trust the fixed blade more. The Manix will make a good companion in my pack, along with WAY too much other stuff (Glock, extra clothes, headlamp, Swiss army knife, first aid kit, lighter, power bars, water, flashlight, GPS, FRS radios, etc., etc.)
Enjoy your new knife! I found the waiting period after I ordered mine almost unbearable. When it finally got here, it was worth the wait!
Have fun out there.