I would imagine your experience, as far as available power and vibration, will be compared to what you've ridden in the past. If you're going to be buying a new one, I think a test ride would be the way to go so you can see what you're dealing with.
The handlebar vibration of the KLR has never bothered me and certainly won't put your hands to sleep, at least not mine, anyway, but I don't hang on to mine too tightly on the highway.
People do it on KLR's (Cabrito posts some crazy traffic-riding videos) but were I to commute on a busy freeway, I personally would be more comfortable riding something with a little more get-up-and-go to use as a tool and an option to possibly extract myself from sticky situations rather than just moving laterally or slowing down, which is about all you can do on a KLR if the traffic's really zipping along. Depends on your particular traffic flow there, I guess. Heavy, high-speed freeway traffic is not my usual riding environment, so I'm no expert on that, but in the few instances I've done it, I was wishing I had a little more available power.
It's capable of getting up to speed on an on-ramp just as quickly as the average vehicle, I would say.
I would add that one plus to the KLR is that when you're in traffic, you're sitting up nice and high and can see things around you and ahead of you better than on a lower motorcycle. It's quite nimble, too.
The only opinion that really matters is yours, so if a test-ride is feasible, at least enough of one to get an idea of the KLR's acceleration, etc., I would try to take one before buying.