The Shure mike would be much better for recording low freq./bass instruments such as actual bass drums or bass guitar amp, etc. The Snowball is an a-ok general purpose/easy-to-use computer mike, but you already know there are better choices.
That being said, if you want to record all kinds of sounds (especially creating your own samples out of home/industrial sfx/Foley type sounds like desk hits, metal clinks, towel dispenser racks, etc.), you probably want a more "general purpose" workhorse. You can go with a condenser, which can be great for "crisp" recordings and things with a lot of detail (vocals, for instance), but you'll need phantom power and a few other accessory items. If you go with a nice dynamic, you will probably save money (at least to begin with), and be more comfortable taking it out and about and not worrying about it handling higher SPL's, as Krushing said. Plus, if you get a cardioid pattern, you can take advantage of mike placement/"pre-EQing" tricks like proximity effect.
But the H6N (I assume you're talking about the Zoom unit) is an all-in-one recording solution; record with on-board mikes (or plug-in your own), transfer to computer, and go to town... I think that might be your best bet. Portable, decent recording, and pretty easy to work with. I use a Zoom H1 for live and field recording all the time and love it. Now they have a firmware update (that probably comes standard on the H6?) that lets you use the Zoom as a USB microphone/simple audio interface directly, so you don't even have to transfer from the card (just record right to computer if you want). So I'd look into that, if I were you.
GJ
