I’ve been riding a CBR125 for almost 10 000km now, through all manner of conditions (everything short of snow, but including a few patches of ice). I’ve never seen Yamaha’s 125 outside of a computer screen, so I can’t really compare the two honestly, but I love my CBR.
The comments in the video about lacking top end and struggling up hills have some truth: I won’t pass anybody once they’re going over 100km/h because I don’t have the rapid acceleration at that speed, but I’ve been up to 140km/h. I’m not sure you’re going to get much more than that from most affordable 125s. If I’m not in the power band already, I’ll usually downshift to go up hills between 6k and 9k rpm. Sure it’s a small engine, but it’s a small bike too, so it does OK. It’s worth noting that I only weigh 140lbs, I have heard of bigger guys having some issues and not really using 6th gear.
The Yamaha looks like it has a pretty sporty riding position. I’m not sure what you’re looking for, but one thing that I’ve noticed on my bike (that I like) is that I can easily sit up in a very comfortable standard position for commuting, and yet there’s enough length to the seat that I can also slide my butt back a bit and get into a pretty good tuck if I want to push it through a bendy stretch.
Regarding handling, I’ve had no complaints at all. For city riding, it’s great fun to have a bike that weighs so little, because I can nip into any little space if I have to, and it flicks so quickly into a swerve if I have to. It would be nice at times to have a bit more juice, but as far as I know you wouldn’t get that from the YZF, and that’s never actually been a problem.
Regarding insurance, I pay about $60CAN a month for a reasonable coverage. If I wanted to have big-time insurance for every nick and scrape I would have been paying half the bike’s value every year. I didn’t compare that to any other little bikes, because I didn’t have the option of purchasing them.
One thing that doesn’t affect handling at all, but that I like, is that the CBR has a full catalytic converter in the exhaust system. I probably wouldn’t ride a 2-stroke because I’d rather not be burning more oil than I have to, and the CBR is crazy better than any emission standards that I’ve seen (I think. I haven’t done too much research on that.)
Hope it helps, and good luck
(Oh, and http://www.cbr125r.ca is a canada-wide forum with some good folks on it. They may have found a way to try the yamaha, although it doesn’t seem to be available here. There’s also some fun stuff about riding through 6 inches of snow, with studded dirt bike tires).