I'll jump in and say get the toothbar. Don't underestimate the advantage of removability. It effectively gives you two buckets. As for structural I agree with Roy, toothbar gives you two cutting edges together which is going to be stronger
A removable tooth bar IMO is the best option. I made my own for $150-$175
I looked up some shanks I liked and teeth/pins. Bought a piece of 3/8 hot rolled metal and welded on the shanks. Pinned on the teeth then bolted the hole bar to the bucket. Slides over and captures the bucket. A couple bolts and on or off.
You can make your own like Chris said.The real cheap way is the scrap yard for some road plate,next is a walk on an old set of railroad tracks for spikes.15 $ for the plate more or less spikes for free.
Fire up the welder and have some fun,
Thanks for the help guys. I'm having my own design cut out at the shop tomorrow from AR-400. This is the stuff they make excavator cutting edges out of. AR means abrasion resistant and it's tough as heck!
Here's a 90% accurate mockup picture. I took some ideas from wr long and tried to size it appropriately to my tractor.