The switcher website is quite slow at the moment; don't forget to press the green Play button after clicking on the respective track under 'maximum volume'.
I just compared iLoud and Beolit 15. - The iLoud sometimes sounds terrible at maximum volume there, completely distorted, depending on the track selected. The Beolit 15 is just a bit less loud, but completely clean. On the other hand, at some tracks I like the iLoud more, as it is more neutrally tuned and has more stereo.

Regarding your other question, differences between Beolit 15 and Beoplay A8 apart from the volume: in terms of frequencies covered, the Beolit 15 is nearly as good as the A8, the bass nearly equally deep, and crisp highs; the mids are a bit underrepresented in case of the Beolit 15, the A8 is a bit more neutrally balanced.
There's one major disadvantage of the Beolit 15: it has very little stereo (some are convinced it is completely mono, but I don't think so). The construction is not designed for real stereo (only one full-range speaker, three tweeters).
The A8 has wonderful stereo, with two woofers and tweeters in a distance of about 50cm / 20 inch.