Congrats on the Bo-Pils! Wanted to share with you that when I went to a tubed manifoild in the mash tun with slits, I was worried about grain husk comming through or clogging too. I took a piece of medium fine mesh copper screen and cut it to lay flat on top of my manifold. I rolled the screen over the tubing at the edges. It works beautifully and I'm able to stir really well at mash in without knocking the manifold apart, since it's only fitted together for easy cleaning. Just an idea for ya.
Yeah, after that beer , I trashed that manifold and bought 5 feet of 1/2 inch id stainless braid from mcmaster carr , and put a stainless spring inside it for support. I bought one of those 48 qt cube coolers because I liked the idea of the more vertical design, plus the hole for the drain valve was already recessed slightly below the rest of the cooler floor. I'm sure I could make another slotted manifold that would work, but I decided that after the first one , I would go back to the idiot proof stainless braid, except , now I have it covering most of the tun floor....it's larger in diameter...and it's supported by an internal spring. I am going to put new focus on getting a good mash extraction, because this seems like the only area I have some trouble (aide from recipe formulation)
I use a cpvc manifold in a 62 qt cube cooler. Instead of slots I drilled holes and put the mainfold in with the holes facing down toward the bottom of the cooler. I've never had a stuck sparge, even when i brewed a wheat beer and forgot the rice hulls that thing flowed freely. I get about 70% eff. FYI Just in case you ever want to try the manifold thing again.
Also a good way to get your feet wet with decoction is to do a single decoction at the end of the mash to bring your mash up to mash out temp. That way you will get the benefit of melanoidin formation without much risk of screwing up your mash if you don't get it exactly right.