Hi jmpaul. As Shadowww suggested, the Elite 1700's would be a possible replacement. Unfortunately I believe they have been discontinued, as well.
Your best bet are the Elite 2000mAh cells. I don't have any experience with them, as I did with the Elite 1700s (as well as the CBP 1650s) but Battery Guy tested some and had good results. They are supposedly good for 15-25A, and as I remember, they did in fact test out well in that range.
One thing to consider when electing to buy high discharge rate cells, they don't last nearly as long as conventional NiMH cells. There is a price to be paid for higher discharge rate capability, and that is, shorter cycle life.
i found the elite 2000mah cells but they are not button top... i also found tenergy 1800mah 10c high drain cells from all-battery dot com but im not sure what the quality of those cells are... i will continue to look
You could always add a solder "button" to the Elites. I've done that with flat top NiMH and NiCd cells, something I don't recommend doing to Li-Ion cells. Just make sure you have a hot iron and go in hot, and fast, so as not to overheat the internals of the cell.
I don't know much about Tenergy's cells. The Titanium 1800 mAh high discharge rate cells had a reputation for leaking though, not from my personal experience, but others here on the Forum. Any high discharge rate cell has the potential to leak, but Cheap Battery Packs' cells have a decent, although not perfect record in this regard.
I used to have my FiveMega 12AA-3D folder loaded with flat top CBPs and they worked fine, no button top was needed needed. Being a 4 wide holder it looks like the 16AA-4D uses the same design as the 12-3D, the cells sit on little separators which have brass inserts. This is different then the 3 cell wide Fivemega holders I have seen where the cells fit onto holes in the holder and there is cell to cell contact and a button top may be needed.
Things might have changed with his holders. Has FiveMega said that you need button tops?
im going to use 16 in a fm 16aa holder, not sure if they require button tops but i think i will go with the elite 2000mah batteries and if a button top is required ill just put a small blob of solder on top
having some problems getting the cells to make contact... added some solder blobs but im still not getting voltage to come through?
its tough making each blob the correct height so all 4 cells make contact... oddly enough once i screwed the battery holder together and i saw a spark?! i quickly unscrewed it and the cells had become warm... not sure how this could possible happen?