I really cannot say enough good things about hempy's. The easy to find and inexpensive materials is just a bonus compared to the ease of use and results. And you can really maximize container size and grow a larger plant with a smaller root base. I have been thinking about containers for my next grow and right now I am looking into 3-5 gallon totes and running a 2 plant scrog.
There are alot of different mediums you can use for hempy. I have only tried str8 perlite and have had great results. Other people use perlite/vermiculite combo or a coco base. A couple new mediums being used are PBRH (par-boiled rice hulls) and mapito. Both are said to hold water better than perlite, with mapito becoming the new favored medium in Holland from what I hear. I will stick with perlite probably, because of my familiarity with it and the ease of obtaining it.
People complain that hempy's are messy but with enough planning they are really not bad. The only mess I have is runoff when I water. A small scale grow like yours and mine should have no issue with watering in a catch pan. I water every 2-3 days and could go longer but I don't leave my rez filled to the brim. You basically can tell when it's time to water by the pot weight.
Let me know if you want anymore info on hempy. I would love to see you run a hempy sCROG with your 150. I bet you could get that light 2-3 inches from the canopy with some good cross-breeze.