The 5001 has a way better tweeter than the crescendo line of speakers, the only reason infinity stopped using the emit tweeter in their speakers is because the company that made them for infinity went under, infinity actually told me their name but it's been years and I can't remember it Lol, heard this directly from the product manager at infinity.
The 5001 does have IMG woofers.
The 5001's midrange is a good design, It's polysperite, basically a graphite/impregnated dome, unlike other domes the polysperite has an extra spider near the voice coil and a outer surround to support the dome to keep it from breaking up or wobbling at higher volumes like other dome mids do, the polysperite mid is light and very quick and wont deteriorate like the polydome.
The 5001's also used Solen metallized polypropylene capacitors in their crossovers for the mids and tweeters where as the Crescendo's used mostly electrolytic caps
The 5001 is covered in vinyl but I have to admit it holds up just as good if not better than the solid oak speakers that infinity made, that is if you take care of your speakers.
Also the 5001's have rounded front baffles that help with imaging and soundstage depth that the crescendo's do not have.
The crescendo series speakers were made for circuit city, the RS (Reference Standard) 5001's were not.
I don't know how the 5001's would sound up against the 3007 because it's really not a fair test as the 3007 is a bigger speaker but it will kick the crap out of any crescendo speaker that is the same size as the 5001, the 3006 comes to mind.
Here is my pair with stands removed