Igniter buttons - I opted to remove the igniters for both the main and side burners and not replace them. I have a handheld arc lighter that I prefer to use. Without the igniter underneath, the buttons droop down. It doesn't really bother me, but with that said, I may or may not in the future decide to remove them and possibly make caps for the holes.
13 flavorizer Bars on a Silver B - I had an inclination that I would prefer 13 bars as opposed to just the five. I have no experience or detailed scientific backing for this hunch, but rcplanebuyer sold the 8 smaller bars to me for a good price and combined shipping with the other ones when I asked him about it, so I went for it. They do not slot into the firebox like the five bottom ones do - they just lay on top of the first set, but they do fit with about an inch of space between the top of the bars and the bottom of the grate. Honestly it may or may not turn out to have been a worthwhile purchase, but my hypothesis is threefold: 
1) More bars = more thermal mass, which theoretically would keep the temperature more consistent when opening and closing the lid, and potentially allow for higher maximum temperatures?
2) More thermal mass closer to the underside of the food = possibly more radiant heat and more evenly distributed radiant heat to cook the food. i.e. more of a "grill" effect and less of an "oven" effect. Maybe better? 
3) More surface area to catch and vaporize drippings before building up in the bottom catch pan = potentially lower chance of flare-ups and more vaporized flavor compounds circulating back onto the food?
If anyone here thinks it is straight-up dangerous to do the 13 bars in the shallower cook box for some reason, I'll reconsider. If not, I'll experiment with 13 vs 5 bars over time and see which actually works better for me in the long run.