I don't see enough information to determine what would be good for you. It's not as simple as that sucks and this is better. You want it really loud? Easy to install? Extra bass-e? Crystal clear?
How much would you make by selling the stuff and how much $$$ would you add to it you purchases; that's the only way to know if upgrading will be a worthwhile upgrade. Also, comparatively how good is the stuff you have, I think it's good for a low budget build.
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The Pioneer will sound like most other HU's in the price range. Not bad at all.
It has 3 sets of 2-volt pre-outs. Good enough.
I would recommend a new HU for iPod compatibility and bluetooth, not because newer units are guaranteed to sound better just because they are "newer".
The RF Punch amp. All generations are pretty well regarded as at least good and the older ones are considered some best amps of the era because they put out much more power than they advertise, sound great, and are reliable.
Sony subs. Even cheap subs can sound great as long as they have a well designed enclosure and are not pushed to their limits (were distortion gets higher).
Reliability is hard to determine for every model sub, but most inexpensive subs are Chinese made and have gotten better over time.
This is what most people need help deciding because they want to know "how loud will it be". Decide on how much space you want to take up and how much power then you can choose subs.