[Inertially]

How do they Riptidz, HJE120, SHE3580 compare?
 
I have a MeElec M9.. are these newer models better?

 

[kmhaynes]

I have the RipTidz, SHE3580 and M9.  My comparison is:
 
SHE3580 is fairly balanced with slightly elevated bass and treble -- everything is surprisingly clear for the price.
RipTidz is bass and low-mid heavy, and reduced in the mids and trebles -- but it responds to EQ on my Cowon J3 very well so that I can make it sound very balanced.
M9 is just bombastic to me.  Bass and treble are very elevated, bass bleeds into the mids, mids are recessed, and trebles are too hot and metallic.  It responds to EQ, but not as well as the RipTidz.
 
The first SHE3850 is the best of the 3, IMO; but the first pair I received were wired bad and sounded out of phase and I had to buy a 2nd set, which are fine.

 

[JK1]

I disagree with your assessment of the Riptidz. Imo it is very well balanced. It doesn't have basshead bass. I would describe its bass as being fast rather than deep. The HJE120 is somewhat bass deficient, however it does respond pretty well to eq. The HJE120 is only 96 db/mw, so it might not play loud enough with some low powered portables, or it might give less battery life.
Most of the other IEMs seem to be between 102 and 108 db/mw. I usually try to avoid earphones below 102 db/mw, and prefer those that are 106 db/mw or higher. Before someone steps in and says db/V is the relevant measure and not db/mw, these are all 16 ohms, so 102 db/mw and 16 ohms corresponds to 120 db/V.

 

[JK1]

The new Panasonic RP-HJE140 is nice.  It is 107 db/mw 16 ohms, and has 10.7 mm drivers. It has much better bass than the HJE120. It is a nice upgrade from the HJE120, although its detail is much less than the new HJE355. The HJE355 is around $20 though, while the HJE140 is only around $8.