Hi DJ Liquid,
I don't know how much help I can be. I haven't used
the SP 303, but hopefully have some relevant information.
You need to identify what it is you are trying to do.
the SP 505 is a completely different unit, designed more for music making, than as a "playing live" tool. I'm sure it can be incorporated into playing live, but I don't think it would be ideal - depends on what you want to do.
I have
a Roland JS 30, that I used to take out. It came out about 10 years ago, and was one of the first DJ phrase samplers, and in essence, pretty similar to the SP 303.
I am now thinking of getting an SP 303.
This is the best way to use it: At home, you record your samples, edit, truncate and normalise them, and set up their tempo. This is not difficult but can be time consuming - however, you'll only need a few hours every couple of weeks for all you need. You save your samples to smart media.
Then, when you are playing out, you have to synchronise the tempo of your SP 303 with what you're playing. I don't think this has changed fundamentally from what I used to have to do: Listen to a tempo "click" of the SP 303 via headphones, whilst tapping the unit in time to the beat. You get the tempo as close as you can to what you're playing - that way all your samples will automatically be the same speed as what you're playing.
The negative first:
This kind of tempo synchronisation is only of limited accuracy - short samples (up to 10 secs max) should stay in time, but you really get noticeable discrepancies beyond this. Ideally use samples of 4 or less seconds.
Further to this, if you try and play looped samples together, they are unlikely to stay in sync, as minor speed differences worsen with each cycle.
You have to keep resetting the tempo of the unit, because of course your playing speed changes constantly - you'll need to adjust it every 2-4 tracks.
Firing off samples in time with the music is dependant on how rhythmically accurate you are. There's no room for error. With practise, you get pretty good at this, but you always have the problem of 1 tiny slip up, hitting the wrong button or whatever can totally screw up a kick-*** mix you're doing.
Another factor in this is that samples have to be edited super-tight at the start. Again, a bit of practise will help you with this, and often you find after a night out playing that there a couple of samples needing re-editing.
The good points
You can be totally original with this.
With a bit of thought and effort, you can soon set up a few banks of samples that will allow you to do performances that are completely unbelievable - mixing in 5 different songs all at the same time, you can really add to house/techno build ups by lacing samples over the top.
The tempo sync problems will be pretty much solved if you already have an accurate beat counter. Better still, if you have a midi output it will be done for you - plus you can sync sequences to the speed of your tunes.
In short, there's a real lot you'll be able to do with it - which is why I'm looking at getting one. Just be prepared for having to put in a bit of effort to really get the most out of it.
Different, but maybe worth looking at is Red Federation's "Cycloops". This has no storage, but allows you to sample on the fly. Because it has built in tempo analysis, every loop you record will be extremely accurate, and will stay in time. It really really works, and could not be an easier way of incorporating sampling.
EDIT
Having just checked a review, there are a few pretty fast ways of working with the SP 303: If you have a pc smart media card reader, you can do all your editing on pc, which would be a doddle.
It will also work out the tempo of a sample based on it's length.
Yep, I'm getting one....