I heard a rumour from someone that knows someone that plays keyboard in a band that keyboard amps are not that good, and that its better to get a guitar/base amp.

Kind of makes sense considering how many guitar amps are manufactured compared to keyboard amps i.e. better technology? most keyboard amps are probably not designed to be terribly loud?

Perhaps the choice between a keyboard amp and a guitar amp is better sound quality vs power (I dont really know, just tossing around ideas).

Just wondering cause I need to get an amp sometime this year(around 100W, my current amp is 40W and I tend to max it out all the time). Any thoughts? Our most common brands of amp here in NZ are Peavey, Fender, and Marshel.

Please don't get a guitar or bass amp for your keyboard!!! But don't just take my word for it, go try one and you'll be convinced as well!

Guitar amps are made for guitars. Guitars have a much narrower range than a keyboard and are very mid-rangy. There is typically only one or two speakers -- usually 12", or possibly 10". You'll get a very "honky" or "punchy" sound with no high end. Also, guitar amps are designed so that when they're turned up to a certain level, they distort. This is considered a good thing on a guitar. But imagine playing a piano sound and having it distort.

Bass amps are even worse. They're designed to play very low frequencies and that's about it. Although there are a handful of high-end bass amps that actually have a horn/tweeter, you're going to get a very muddy sound.

Keyboard amps can sound very good. They're made for keyboards and can reproduce a full range of frequencies. Some can get very loud as well if that's a concern. I'd encourage you to try before you buy.

Nic,
I'd second the opinion of SteveY. Right on. I have two Peavey KB-300's[300 watts]. I don't play in a band but I use them frequently. One I keep at home and the other I keep at the church. My school also has one.

Try one out in a store first before you buy. The KB-300 has plenty of power.
ej