Yes griefing there counts! Stealing is stealing, Destroying others work is destroying others work, and it doesn't matter where. unfortunately if you didn't get a snapshot of them doing it (use f2 for fast screenshots in minecraft) us moderators can't do anything about it. we need proof to ban someone (and we will)
The best place to build nether stalk farms is definately as close to spawn as you feel safe, because there is a chance that all of the players passing through the area will activate the chunk the farm is on and stimulate their growth cycle. It is also more risky of course because if someone has a slow connection and their internet lags, they may see your hidden farm before the chunk fully loads and grief it. (or use illegal texture packs to see it) At least alot of people are supprters and have the option to hide themselves on livemap, but in the end it is always best to only make the farm using materials/nether stalks you are prepared to lose, because then you wont be overly disappointed if you find it trashed. Ideally utopia nether, but when that isnt an option all the smp servers are pretty much the same.
I made mine on SMP4, and it really helps with my shop on smp2. it allows me to make my netherstalk really cheap, atm its about 10 - 12r as i post this. you do have to be near your netherwart for it to grow, and, correct me if i'm wrong, but lava does speed up the growing process. It is in a very unusual place and people do walk past it but the hiding place is so genius its never found . i know i shouldn't, but i do keep a chest there with valubles and TONS of netherwart there.
maybe we can rig a group nether farm... or nether plots that are 10x10 but for an hour or something and it costs 100r??? just an idea...
I like the idea of netherplots, but if we were to get one I would want it forever, not just an hour. Maybe for a fee.