New Brew Kettle Build

I just acquired an old keg (my uncle found one in his shed hes had for 10+ years and donated it to my cause) and am going to be cutting/drilling it to make a brew kettle to step up to 10 gallon batches. My question comes in the valve, is it worth the extra money to go with the 3 piece or doesn't it really matter since the valve should be heated up to kill anything that may be growing in the bowels of the valve? Thanks.

2 months ago, I would have said, "no it's fine". Then I actually disassembled on of my valves. Despite rushing water through it at the end of a brew day and then some strike water through it for waste before mashing in, there was some gross stuff in there. I don't know if it did anything to any beers I've ever made, but now that I know it was in there, I'll be disassembling and cleaning them after each brew day.

*edit*
My mistake, I am thinking of the 2 piece. I don't know what the benefits are to the 3 pieces other than being able to tear them down farther for cleaning.

I've got a 2 piece 1/2" SS on my BK and MLT now, but I just picked up 2 new 3 piece 1/2" SS ball valves on EBay for less than $40 to replace the 2 piece on my BK and the other for a fermenter I'm making from an old Hoff-Stevens keg. I'm OK with the one on MLT staying a 2 piece because anything that goes thru it gets a 60 min + boil to kill anything. However, I'm not conviced that the BK valve ALWAYS gets hot enough because I use a heat shield under it and, along with an immersion chiller, everything that goes thru it at bug friendly temps winds up directly in the fermenter.