I can't find any info on this either.
I used to use a Sharp microwave/convectional and I really liked it. If I needed fast, I got fast, but most of the time I used convectional. It takes longer of course, but cooks a lot better. So, microwave power doesn't matter much.
Delonghi does seem to have lots of people who like it and lots who think it is junk, so YMMV. But, it seems like a good price IF quality is there. The Sharp unit I used was a bit larger (1.1 cf as opposed to 0.8 on this Delonghi), but it sells for over $300.