How Much Is Too Much?

I recently bought a JL 10W3-D4 Sub and am picking up a Thunder 6500D MTX Amplifier Tomorrow. I know from experience that over powering can be a good thing as long as gain and crossovers are set properly to compensate. Many of you familiar with these two products will see what my next question is going to be: How Much is Too Much (Power). My Sub is rated at 250W RMS and My Amp at 500W RMS. The Circumstances are as follows:  I am putting the sub in a sealed enclosure (built to spec), the sub in question is going to be a dual 4 ohm voice coil sub wired in parallel to produce a 2 ohm load. 

Amp = 500W RMS x 1 into  2 Ohms at 12V

Sub = 2 Ohm 250W RMS 

Anyone see my concern and wish to elaborate? Like I said I've over powered before but I am wondering if I may be pushing my luck? Anyone in the group had experience with similar if not exact same products? Thanks in Advance.

                                                                                                      Colin a.k.a. bLaZ