is there any difference besides accessibility of L9 coming from the side?

On the FiiO L3 there are two buttons on the side that you need to press in order to release the 32 pin connector from your iDevice.
 
With the FiiO L9 there are no buttons.

thanks

the problem i find with LODs of the style of the L3 and L1 is that, when it's actually in your pocket with your ipod and you're moving around a lot, tension tends to get pressed on the cord (since it sticks out from the rest of the gear), and this leads to issues. I went through about 3 or 4 L1s, each of them malfunctioned within a week due to this problem (granted, it was at my job, which involved constant physical movement, bending, lifting, etc, for 6~8 hours a day). After that I ended up getting a custom LOD that was like the L9 (which didn't exist back then). When the L3 came out I bought one because I wanted to use it in the car (L10 wasn't out yet), and I was curious to see if the thicker cable would alleviate the problem that the L1 had. Well, I used the L3 at work for the first time today, and what I found was that it was not uncommon for the LOD to become partially unplugged from the iPod, regardless of the fact that it has the little buttons on it. Just a few minutes ago I ordered an L9.
 
So, basically, if you intend to use this setup on the go and be active with it, I believe that the L9 would be a more durable design because the cable does not "stick out" from the rest of the bundle and thus is less likely to be jostled or damaged in your pocket.

My experience with the L3 and the L9 is that with my new 7th Generation iPod Classic, if I use the Line Out Dock Connector with the buttons for release, even though it doesnt dislodge, the L9 would sometimes lose one side of audio on my headphones when I moved. Their might be a slight difference in the pins, as I know the connector visually has not changed in years, but some of the pins were not used/have specific purposes that may be different between different generations of iPods. I would go with the L3(or whichever connector type came with the iPod, (I.E. the stock cord had buttons to release, get the L9), as it should be backwards compatible as opposed to the L9 which may have a compatibility issue if what I believe to be true is actually accurate. My boss at work, while not in reference to iPod connectors specifically, says that during his Apple Certification training they teach that Apple products are usually backwards compatible, but not always forward compatible.