Not just tincans - even against mail, I believe bodkins will do more damage. Tatar arrows and others are best used against horses and lightly armored ranged infantry. If you are HA, it makes it much easier to choose low armor targets. You also save cash on arrows by not using bodkins. It helps since your horse will cost you a lot in repairs.
I've done 8 PD foot archer and I loved using tatar arrows and longbow against horses and low armor targets. Higher PD multiplies your damage more, so the few extra points of cut damage are a bigger difference. If you go for 10 or even 12 PD, tatar arrows will pack a nasty punch.
If you are going 6 PD or less as a foot archer I'd suggest bodkins. No stress on finding targets. Plate armored guys rarely use a shield so you can just fire on them. Use one stack of arrows when the server has 60 or less people, two stacks of arrows if you are facing more enemies. You probably won't need them even then, unless the map has good archer nests.