16-bit vs. 24 bit

24 bit is useful when you use a lot of digital effects - but only if the effects are done in 24 bit.
It's like when you do a calculation, when you use more digits behind the comma, it's getting more precise. In audio this means less artefacts and quantization noise.
The drawback is that 24 bit files are bigger than 16 bit.

Resampling is always a compromise, you should avoid it. IME it's better to downsample from 24 to 16 than vice versa.

You will resample to 16 bit when you burn a audio cd, so you can keep it 16 bit all the way when you don't use any 24 bit digital effects.

Also, even if some machines claim to be 24 bit, they may only be 24 or even 18 bit - and AD/DA converter quality be still differ anyway. Some highend 16 bit converters will be better than mid- or low end 24 bit ones.

 

Yes, CDs are always 16-bit 44.1kHz. Normal CDs, anyway. I don't know what SACDs are.

Might I suggest you look into the Roland VS series...

http://www.rolandus.com/products/subcategory.asp?catid=12&subcatid=48

I don't know about prices, or what your budget is, but maybe the 1824 would be good for you?

I use a Roland VS recorder (the VS-2480CD) and I love it.

In regards to the difference in quality between 16 and 24 bit... Well, some people will tell you it's a huge difference, and that they can't live without their 24-bit 96kHz blah blah blah. And some will tell you that it makes little difference.

I'll just say that great sounding recordings have been made at 16-bit.

24-bit is better, from a technical point of view, it gives you a lower noise floor which means more dynamic range. It is of more benefit to you perhaps when you're using a lot of digital effects, like JMX says.

CDs are 16-bit, so in order to produce a CD, you will have to dither down to 16-bit - even so, you do still gain quality by doing the recording and mixing at 24-bit. It's about cumulative errors, you see. The lower resolution you use for all intermediate calculations (i.e. any processing done during mixing, including effects, EQ etc), the greater the accumulative error. So if you record and mix at 24-bit resolution, you still get better accuracy even when you downsample to 16-bits.

As to whether that accuracy is important or not - well, you have to decide.