I’ve had a 202 and 303, and I’m now on a 404SX. I don’t really use it very often, but it still has a place. The features and workflow mean that you’ll often get something quite different from what you’d achieve on the OT. Of course it’s a lot more limited, but that’s what leads you down a different path.
I like having the 404SX hooked up to a portatable turntable, ready for sampling at any time. I think it definitely lends itself to vinyl sampling, and since my turntable has a fairly shoddy built-in preamp I don’t really miss the vinyl compressor of the 303 - my samples arrive in a state of distress of their own accord. It’s also fun to sample a bit of live SP noodling into the OT.
I’m always wary when a piece of equipment gets a reputation for ‘character’ - it can be true, but I suspect the SP-303’s popularity is based as much on artist kudos as it is on genuine character - people think it’s going to give them Madlib in a box, but I feel he’d be doing just as well on an SX - he’d just be doing things faster. The SX has boundless potential, if you can get behind the workflow. I sometimes think of the OT as an uptight, OCD device and the SP as its laid-back country cousin - you’ve got to get into the right mindset. Hopping between them, I don’t know, perhaps it keeps your mind nimble and helps you avoid getting stuck in a rut. Other times you might find yourself fantasising about what you could achieve if the SX had a waveform display or would just let you resample a sequence for Chrissakes.
If I had to buy another SP, I think I’d stick with the 404SX. I certainly wouldn’t want to go back to the deathly crawl of Smartmedia - SD cards are cheap and huge. I don’t mind trimming and chopping by ear - I quite enjoy it - but waiting around soon gets old, and the SX is a major improvement there. I might be tempted to check out a 606 or 555, but they still tend to be pretty costly. I think the SX has a good mix of price, features and design.
The real question is whether I’d buy an SP again at all, and I’m not sure - I bought mine before my OT, and the OT obviously added a lot to me setup. If I’d had the OT first, I’m not sure an SP would have been on my wish list. Hard to say.
In short, I think the SX is a better option than the older models if you want to get things done. I guess if all you want to do is grunge up a beat, the 303 might work out, and it’ll definitely keep its value. I don’t see the SX becoming a vintage treasure, but it’s a solid and flexible machine for the here and now.