well i do have a sump, but i was interisted in the deltec mce600 because i heard many good things about it and being that my sump already isnt that large and is cramped it was attractive to see a HOB skimmer that seems to perform so well.
I think the Euroreef will outperform the MCE, but there is the practical advantages of a HOB you mentioned. Still, if you can make the room, I would recommend the RS100 or a smaller Deltec in-sump skimmer.