I would go with the 3021 for the extra height, if you want an "all around" tripod. You can always partially collapse the legs if you are shooting at a lower altitude. I got the black version for its stealth when setting up outdoors since it doesn't reflect light like the bare aluminum version. The green cammo version looks cool, but kind of out of place when setting up indoors for a formal shoot unless you've got your M-16 with you. As for the pros and cons of shooting with the center column extended, I've never experienced any problems as long as there's no wind. Theoretically, you could get some minute movement from mirror slap when the shutter fires with the column extended high, but in practice I have never seen any visible evidence of this. You are more likely to get motion introduced to the tripod from someone walking across a hardwood floor in the same room where you're set up. When my kids were young, they could make the record needle skip on my audio system when running through the house.