While tuning the 346XP, I hit metal and had to file the chain, so these times can't be compared to those from Saturday.
My initial reaction after running both saws was that the 5100 beat my 346 badly. It feels that strong in the wood. I was so convinced, that I tore the topend off my 346 before going in the house to time the cuts. I've been wanting to go back in it anyway.
Imagine my surprise when cut times showed that the 346 was faster! This is just another example of how what someone thinks is faster means nothing until they put a stop watch on it.
You'll notice that my 346 is tuned on the lean edge. I only do that when going for cut times. That's a disadvantage to the 5100. I won't dare try to tune the 5100 on the edge when cutting wood this size, simply because I can't tune it by ear and verify it in the cut. The rev limiter kicks in before that point. In the real world, it doesn't matter. I'm not going to run a saw that lean when actually doing work.
You'll also notice that the wood was a little cleaner for the 346 cuts.
I've not yet played with ignition timing. I've been told by at least one other that they don't like it, but I still want to try it before calling this saw done.
With all of that said, I think this 5100 makes a better all around firewood saw. While it's not faster, it's definitely torquier, and it's plenty fast enough. I really like operating this saw.
Some builders don't like to do direct comparison videos for fear of making one saw look inferior to another, and thereby hurting the reputation and sales of port work on said models. I've never been one to pull punches on saw performance. I've done my best here to demonstrate how these two saws compare, and then verbally give you my assessment of how they might compare in actual use. I hope you are able to get a fair picture with what I've shown and said here.