mjs020294 makes a good point. I got the 150 shortly after it came out. One day I was doing maintenance with my hands in the water and got a nice jolt. Checked out my equipment to find the insulation cracked exposing the wires inside. Coralvue made good on it and sent a new motor which I haven't had issues with so far. They changed the insulation to a more resistant rubber to cracking.
Anyway all that being said I have a 65g and the 150 is nearly overkill. I absolutely love it though and my coral does too (I have a mix SPS/LPS tank more dominate in SPS)! I alternated the paddle wheels and they send a softer more turbulent flow from two different directions per wheel as opposed to one strong stream with the regular configuration. Works much better with my 65g. I have zero dead spots and it's a heavily stocked tank with rock and coral. Your 130 will be more than enough in a 40 breeder. Remember what I said about the reverse paddle wheel configuration if the normal way is too much force.
Far as snails go, I have not had an issue but do be careful with the fins because they are fragile and can break fairly easy if handled too rough.