Hm. First you say that the point is code quality, not speed, and you should only optimize bottlenecks, and then you start giving advice on using data structures that you haven't even worked with or benchmarked yet...
Because the point IS code quality, and because I haven't run on speed problems by now ?
If you really have to optimize speed, you should do your own test and check where the bottlenecks are. Because the data structure for your updatable list is probably not the cause: nobody gain 20 FPS by switching his LinkedList with two ArrayList.
But sure, it probably help if you want to run your game on a lower end PC.
As a matter of fact I did my own benchmark on this matter. Most of the time, the gain between using an ArrayList and a LinkedList is negligible. Even with a simple iteration (296 ArrayList / 315 LinkedList), which I just tested right now.
And by negligible I mean negligible on a modern PC, don't get me wrong.
What I haven't benchmarked yet is the potential speed gain of using a LinkedList to remove objects during the iteration.
I think the gain is so negligible I should'nt bother with it at all. Athough that's just a theory, as I said I should write a benchmark to be REALLY sure about it.