If you had to pay each porter something outrageous like $250 per day, then you would be striving to cut every ounce out of the total load in order to minimize your porter bill. However, porters aren't that expensive. Most of us going to Kili have had to fly halfway around the world to get there, at moderate cost, so the need to pay an extra porter here or there is not likely to be a big deal. So, rather than take the most UL equipment, you might consider taking some "moderately light" equipment that might be more reliable in the face of adverse weather or other unforseen factors. Hey, if one extra porter gets hired, he supports his family for about a month on the pay.
When I went up Kili, I was on a trek, and the outfitter had hired all of the porters, so I didn't even know what porters were getting paid. All I know is that we were told a maximum duffle bag weight to pack for, and everything additional would have to be carried by the trekker. I had a puffy down jacket that I was not using, and when somebody else got sickly cold, the jacket got used.
OBTW, at the end of a trek, it is customary to tip your porters something. Credit cards don't work. Travelers checks don't work. They will accept US greenbacks, Euros, or maybe local Tanzanian shillings. In some cases, the porters and guides did great, so they scored some cash.