i have a 20" factory bar on my homelite XL12. it cuts well.. but in my opinion.. the XL12 will be great with a 16" and a super cutter with a 12". just keep in mind this example, if you have a 16 and go to a 20.. that may be 4 inches longer bar.. but thats roughly 8 inches more chain (taking into consideration 4 inches more chain on top, and 4 on the bottom) and thats a LOT of drag added! i also found an echo bar fits MUCH better than the orig homelite bar! and the oil holes match perfectly, same drive link count and all. the slot is just too sloppy on my factory homelite bar, the echo is a tight fit and leaves nearly NO up and down slop, the homelite bar has over 1.5 of up/down play at the end of the 20" bar.
for refrence, the new bar im comparing with is intended for an echo CS510, oregon power match plus.
200RNDD176
homelite bar is a Homelite "Power Tip Bar" with no numbers stamped anywhere.