I would also suggest the ZMA-R.
Hassle free is the word for it..as someone rightly said earlier..!

And as far as the R15 is concerned..it does not have too much of a maintenance, apart from the regular chain cleaning and lubing.
Although, riding R15 on bad roads may be a pain initially..but nothing that one cant get used to..!

Thogh I am a big fan of YAMAHAs and think that the R15 is a really good bike but my take on your requirement would be to choose the ZMA - R simply cos the R15 is derived from a racing DNA the famous R1s and the R6s whereas the ZMA R comes from a dirt bike lineage the Honda CRX 230 i think and the basic engine ca=harecteristic will suit your of roading needs better. On dirt you need ample low end grunt for a bike to be effective but the R15 makes most of it's power in the higher revs, like you better suited on nice tarmac long starights hard braking and dive into the corner kind of riding. I would suggest you go for the ZMA R but if you are open to other bikes consider the FZ series the bare naked FZ16 in partcular it s got lots of usable power in the low and mid ranges and is a very stable motorcycle.