First off the SV is cheap to purchase, especially used. It is also cheap to insure. Most insurance companies rate it as a touring bike or standard
The SV is a very forgiving bike to ride. It has great engine braking. Say you get a little hot in a corner. Just rolling off the throttle will scrub alot of speed, without hitting the brakes. The SV is very good on gas and if you do spill it, parts are cheap and plentiful. I lowsided my SV at the track. $50 for a new rearset and I was good to go. To put it in perspective a friend of mine lowsided a F4i at the track and it cost $500 to get it back looking decent, and that is with used parts.
As far as the weight, depending on what kind of riding your doing, weight can be a good thing. In the twisties, yea lighter is better. On the freeway or long range riding, heavier bikes fair better IMHO. The heavier bike will generally have a smoother ride. The lighter bikes tend to get blown around and bounce more on the freeway.(suspension set-up dependant).
Inlines in general are not a very good engine to learn how to ride on. The power is not the problem, it is how the engine makes the power. The rr can be ridden very dosal. As the bike revs past 7K rpm's things get to cooking pretty quick and that is when things go bad. The power really comes on strong and can catch you off guard. It is hard to explain, and you can go into it with the best on intentions and still get over your head. I am not saying you can't learn on a 600rr, but you will learn more, faster & safer on a bike like the SV; than on the rr or F4i for that matter. The rr engine doesn't make much power down in the revs, but once it starts, look out. The F4i makes more down low, but still has a punch up top. The SV has a nice smooth power curve, no surprises, just smooth usuable power.
If your under the impression that the SV is not fast, you are mistaken. I rode with 600, 750 & 1000 inlines with no problem. They would smoke me in the straights, but I'd be right on there arse in the corners.
As far as altering the riding position on the rr. The rr is the way it is so that you have plenty of ground clearance for leaning. Granted it may not hurt inthe begining to lower the pegs, but as you progress it may cause problems. Dragging hard parts may sould fun, but levering the rear tire off the ground bacause you peg is dragging....sucks. Either raise the pegs higher or leave them alone, never go down. IMHO
A little more on the SV, the SV is just an easy bike to ride. You can make midcorner changes easily, braking is crisp (with front lines) all tis is due to the weight of the bike. The engine is strong and smooth, not to mention bulletproof. If you roll off the throttle of an inline 600, you almost speed-up
NO engine braking. I would often ride without ever hitting my brakes. I had someone ask me once if my brake light worked?
I'd slow down, but the brake light never came on. The engine offers the ability to slow down midcorner if needed without using the brakes. Using the brakes midcorner should be left to later in your riding carrer. For now you want all your braking to be done before the corner entry. The SV also helps build confidence. Riding is probably 90% mental. If your riding on a 600rr, and short shifting it, you know in your mind that your riding around on egg shells. Always aware and consious of where you are on the tach, that is attention that is needed on the road and your surroundings.
Get a used SV, cheap, haggle on it. Put at least 10K miles on it, and after that maybe step-up. 10K miles will go by in no time. If you ride much
Maybe do a trackday or two. I would wait until you had some substaintial riding under your belt prior to the trackday though. The new bikes will come, and there will always be something out there that lights your fire. The 600rr is not the last bike you will ever love.