For me abs is definitely not a deal breaker. I owned an old EX500 as my first bike and it didn't have abs. Never locked up the brakes on that thing. I am in no way anti abs but it definitely is not a requirement. Not having abs forces you to learn smooth and controlled braking. Having it means you can rest assured if you know you aren't smooth you can jam the brakes on and not lock the brakes up in panic situations. Keep in mind it isn't your anti crash feature. There are plenty of people who have crashed braking even with abs on. The low end abs systems won't work too well when leaned over. Some manufacturers have improved on this with systems that can tell when you are leaned over and even modulate braking for you then.
As for the slipper, they are a nice feature. I had one on my older bike. I would say its probably more beneficial on the track. On street if you are really aggressive with downshifts and don't know how to be smooth it could help, but then you are just using it as a crutch rather than learning how to be a smooth rider. I have also owned a few bikes without a slipper. On one bike without, I have downshifted a bit too aggressively more than once and that bike had enough power to really fishtail the rear end. On the R3 it was much more manageable.
As is, the R3 is a well made bike for a new rider. Adding abs to it, or any bike for that matter makes it better. A slipper would be icing on the cake, provided it doesn't add too much to the price.
As for the slipper, they are a nice feature. I had one on my older bike. I would say its probably more beneficial on the track. On street if you are really aggressive with downshifts and don't know how to be smooth it could help, but then you are just using it as a crutch rather than learning how to be a smooth rider. I have also owned a few bikes without a slipper. On one bike without, I have downshifted a bit too aggressively more than once and that bike had enough power to really fishtail the rear end. On the R3 it was much more manageable.
As is, the R3 is a well made bike for a new rider. Adding abs to it, or any bike for that matter makes it better. A slipper would be icing on the cake, provided it doesn't add too much to the price.