Wow alot of posts its hard to keep up....
I agree with you that minato's speed an reflexes would be a problem. I set out my post like that so after finishing the reader was able to take all the different parts into consideration and form there own judgement. When taking all of these factors into consideration myself, I would say Tobirama still with extremely high difficultly. This is based on the fact that I think he is an overall more rounded ninja (and therefore would have more options), but in saying that Minato is very very strong. I guess it comes down to personal opinion. Also in regards to Minato sealing the edo, doing so would create and opening for Tobiramam and the distraction could be fatal.
Hey I just had a look and the sword was mentioned in a fillerU_U, so I think i may take it out. Still unkillable s-rank jounin aren't to be sneezed at, and the time it would take for minato to seal them would give tobirama an opening. Also the only seal he has shown that would help him seal them is the reaper death seal, which would kill himself, so I don't see him using it unless it was a last resort.