When on Soundclick for instance, the export they recommend for optimal translation is 160kbps bit rate, and I usually set the sample rate at 48000. It is usually the best translation.. However the audible difference in the studio when compared to a wave file is like night and day, so much more perception into the depth of a wave file than I think MP3 will cover, the compensation is alright it mp3 just doesn't bring the detailed clarity of your work for other listeners on the internet to appreciate as well.
Thanks
LWD