Bigger carb? dude if you dont need it, dont get one.
I wanted more power with my 2001 yz125 so i bought a yz250.
Port jobs will not hurt the reliablity of your bike. Flotek did my shee and it runs w/o any problems and i beat on it.
I want to get my yz250 ported but i like my very very smooth powerband
A port job is your best bet. It's cheap. With the money you spend on a big bore, you could sell your 125 and buy a 250. I sold my 125 for $1700 and bought my 250 for about $2400. Well worth the money!