My room is about 14' x 18'. Home theater use only. Is this sub adequate?
More than adequate. I started with a single plus in my room that is of a similar size as yours and it was great. I now have two in that same room and it's even better. If I remember correctly, Outlaw typically will have a sale on these and the EX model (which is a step up from the plus) sometime this summer and you'll be able to save even more money. I believe the summertime sale is freight free, too.