Burner questions

I have been doing as much research as i can but i am still a little confused. I am looking at one of the Bayou burners but cant decide what one to get it is between the SP10 and the KAB4, i have a 15 gallon pot and am only doing 5 gallon batches but soon will probably do a 10 gallon sometimes, i would probably rather get the bigger KAB4 but i have read around also that it is almost to hard to do a 5 gallon batch on it to keep a constant lower temperature or even keep a good boil without a boil over. What is all of your thoughts on what burner would be better for me.
thanks

Don't know I'd thus helps, but I got mine at Lowe's, 50,000btu. Came with a pot or something to fry fish I think. Was $60.

I had the SP10, it worked great for my uses with a keggle.