Oh freddy! This is probably gonna start a debate....
What's wild is the majority of the studies I've read somehow proved that patients switching to oral was beneficial for both serum B12 levels and financially. We can throw the financial part out of the window because you wouldn't be paying to be injected. Your cost is B12, syringes and your time.
I've taken as much as 2000mcg orally ED during a 12 week cycle. I've also taken 1000iu intramuscular ED during a 12 weeks cycle. I have a much better overall well being when injecting. I get panels fairly regularly and I can tell you that there is no placebo here. For me, IM B12 is far superior.
Hope that helps.