Yes, 1,000 is worth it
I have the shaker 1000 in my 05 sonic blue and it is worth the price for several reasons.
First, the speaker placement. There are more speakers in the doors, front, back and seats than the 500. So, to replicate the speaker placement will require cutting in your interior. Do you really trust installers to cut your interior?
Second, fit and finish of the consol in the dash it fits period.
Third, crank it up to full volume no vibration/rattle just clean sound but you'll go deaf.
You will spend at least $1,300 if you plan on upgrading and I doubt you could do much better than the 1000