+100
An R1 for a beginner is suicide. You'll be dead soon. There's too much power under the twist grip. I'm a beginner and have only been riding a couple months, and there have been times I screwed something up and having 20hp instead of 180hp has saved me. I've seen 2 people killed on motorcycles right in front of me--One when I was a kid, about 10, a guy on a Harley smashed his head open right in front of me and my little brother while we were playing in our yard. The other was when I worked in Paris and was just coming out of the Metro and this jackass loses it and slams right into a cast iron light pole right in front of me and never moved again.
I've ridden offroad before and it is totally different. No offroad bike has the guillotine power of an R1, obviously, but the cars and the deer and the fenceposts and the wind and the much higher speeds and extreme variances in traction make on road riding much different than off-road riding. Offroad experience means you will do really well at the skills test of the motorcycle exam, but none of those skills will save your life on the pavement. Not anymore than insane knife fighting skills will save your life in a gunfight.
The worst thing about riding on the road is the drivers of cars. I wear a bright green florescent vest and people look right at me and then proceed to run me over. Cell phones and such are way more interesting than the objects outside of their windshields. I could be on fire with big, oily Hollywood explosions pouring off of both sides and someone would stare vacantly at me while turning left right in front of me. You better become an expert at identifying threats and learning to swerve and brake before you worry about becoming the next Ghost Rider. One accidental twist of the throttle, which I have done, while swerving, is only a slight mistake with a 250. With 180hp it might have thrown you under a semi.
Motorcyclists have a 37X higher death rate than automobilists. The skills test is easy (especially with dirt bike experience) and the written test is tougher, but easy if you study a bit. That's an easy way to get your endorsement. I did that, but still didn't feel like I knew what I was doing. My parents have been riding for 20 years and they told me to take a class. I took the ABATE class and it was well worth it. It was funny to watch Harley guys ride to the class on their 700# cruisers and then fall off of the little 125 and 250 bikes doing the slow-speed maneuvers. It was fun to thrash the state's motorcycle in a big empty parking lot, and I learned a lot about what a motorcycle can do on the pavement. The best thing about the class was, though, their approach to strategy. Mad skills and a 200mph bike don't keep you from being killed. Understanding you inexperience and building your experience by putting your bike in the most visible spot on the road and, so, keeping alive build your experience.
Start by enjoying a motorcycle for what it is--an engine and 2 wheels--and learn how it operates and becoming a part of it--and also realizing that you aren't a part of traffic because nobody sees you. You are totally alone out there and basically invisible. Once you have these things in hand, adding a couple hundred horsepower might keep you out of the 37 riders that die for every car driver.
Myself, I'm really happy with 20hp. It's not about what you are on, to me. On a bike you aren't protected by a 5-star crash rating. You're basically naked and relying on your observation, deduction and skill to keep you alive. I have 5 kids and 8 nieces and nephews nearby. I have a 15 passenger van that I actually need, and that's kind of sad, because I'm not a church. I ride my motorcycle in any kind of weather anytime I get a chance. It forces me to forget about everything else and concentrate on staying alive.