Powershot SX120 IS VS SX150IS

Hello folks.

While I didn´t find my compact „camera to buy“ after photokina camera announcements, I decided to grab second hand cheap one and wait for next releases hopefully at the begining of 2013. I foud that I can get Powershots SX for about 75 bucks, which is pretty fair.

I found SX150 IS review here, and it looks like it makes up for todays compacts (TZ30, HX20V in terms of IQ and noise, especially at lower ISOs, maybe better than new machines, which is only what do I care about now. I don´t need wide angle, will struggle a bit for new effects (miniature effect, HDR multiexpositions etc). Anyway... I like the IQ and noise amount of SX150 IS, which is 14Mpx 1/2,3“ sensor.

Can anybody help and tell if the old one 1/2,5“ 10MPx „maintains“ the same amount of noise please? I like it more because of faster lens, but I´m afraid of this tiny sensor.

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Why does he do it?