if you listen while being alive, i.e. while breathing, having a heartbeat, maybe even eat some crips, or sit in a transportation vehicle, or walk through a street while listening to your iPod, lower quality settings are very unlikely to bother you.
I have pretty good ears, but I cannot really hear the difference between mp3s encoded at 224kbps and anything above that. And if I can, I'd be hard pressed to call out which is which. Probably would have a hard time picking out the 198kbps if it were among there.
As you will still have your uncompressed source at home in the shelves, to which you can return when you really really want to try and hear that guy in the pommes-frites boutique across the street from the studio order a double with all on top and then listen to his accompanying burp roll off, as it was recorded through the open window of the studio on a hot day in May, I'd say go for quantity and be happy with quality merely being good enough.
Kidding aside: Having someone make you a blind test disk with various encoding options may help you identify the best setting. You may be surprised.