reloader;
The CRKT M16 Series, are definately great for the price.
Recently, I believe CRKT made changes, and I think it involved changing from Aus-6 to Aus-4, to the dismay of many, and this was even discussed a short while ago in this forum, as well as recent discussions on the CRKT M16 line, with the majority of people supporting the notion that the M16 is one of the better, if not the best, knife in CRKT's product line, simply due to it being a fairly good quality knife, at a relatively inexpensive price.
In terms of the M16-Z's, with the zytel handles, I have read a couple of reviews which noted that these performed fairly well, considering the cheaper price, and the lower quality of steel, which was previously Aus-6. It is a shame that they have now been lowered to Aus-4, since the Aus-6 Zytel M16's made reasonable knives at that price range. Ideally, the best advice would be to go with the Aus-8 blades, however if a cheap product that is of average quality is what you are after, any of the M16 line is a reasonable purchase, IMO, I would suggest that if you don't want to purchase a aluminium handled M16 with Aus-8 blade, you at least try to purchase one of the Aus-6 zytel models first, rather than purchasing the later Aus-4 models found in Walmart.
I own an M16-13SF, which features Aluminium handle, Aus-8 tanto blade, with dual Carson flippers. You inquired as to the tanto and it's usefulness, and there are some contrasts to the spear point blades, in that the tanto, in my opinion, is not as useful to the average person, as a spear point would be, especially for EDC, and daily use, and it is also more difficult to sharpen, and with the M16 tanto's, the 2 grinds are also on different angles, which make it even more of a hassle.
"Mentor" also stated that the spear point blades are chisel ground, and the tanto's are dual ground, however from my limited experience, the tanto's may be dual, yet the grind is definately not a proper v-grind, and can nearly be viewed as close to a chisel-grind, since the backside angle is hardly even noticable, and whilst not a full chisel, it is neither a full dual/v grind. So in my opinion, and other's I have discussed with, agreet that the spear point is generally much more useful in daily duties for the average person, and as an EDC, rather than a tanto grind, which is more specialised IMO.
I definately suggest you do a search on the CRKT M16, as there are many discussions on this particular subject, and some fairly recent discussions which mentions all of your inquiries, with alot of beneficial views, opinions, and information.