I have no idea what kH and gH are.
I just have a very basic TDS meter. We had a water softening system that **** the bed on us a few months back. Consequently, I got an RO/DI system for gardening, cleaning, drinking, and other such nonsense.
over 200 seems like its Very hard water. Do you get mineral deposits if you don't dry off fast enough when you get out of the shower??
No, nothing like that. The TDS would have to be something around 800 - 1000 to start seeing visible deposits, at least to my knowledge. Our water is right around 200, which is the beginning of hard water. 200 isn't out of control, but for most stuff beyond washing dishes and making Kool-Aid, some type of filtration is required. When I was in college, I lived in this crappy old house, and the TDS there was nearly 700 PPM, and I still wasn't running into major problems on a day to day basis...certainly wouldn't have used that water for anything but bathing and washing dishes, but nevertheless.
Also remember, RO,DI water is almost oxygenless (dissolved) and has only a few minerals if any left in it.
An advantage of RO is that it really steeps stuff well, because there aren't minerals present to impede osmosis. For the most part, there are probably enough minerals in the extract component to get the job done, but in the future I'm going to use about 2 tsp of Burton's salts. The brew that's in the primary now -- an oatmeal stout -- was made with RO water and no additions, besides the obvious stuff imparted by the grains and extract. Fermentation is proceeding fine by all accounts, so I suppose I'll just have to wait another 7 or so weeks to find out if it's a turd (or a gem).