A couple things:
First, I don't even know if there is compression on the Rumour at all, so you should really take a a careful look at the list of presets. I wouldnt' consider it a compression box at all.
Second, neither unit is dual processor. There's one processor that runs in some cases a couple of effects. So however the effects are set up in the presets is how you have to use them. Of course, they have a lot of parameters to edit, but you have to work within how they laid out the effects.
I personally wouldn't buy a multieffects box for compression (although the Mangler and KSP8 have excellent compressors).
From your posts it sounds like you are pretty specific about wanting compression and reverb. The Rumour is a superb reverb box, an incredible value at the price in my opinion. However, for compression I think you really need to look elsewhere.
My suggestion would be to pick up the Rumour for the reverbs and then locate something like
the TC Electronic Triple-C (stereo version). This will give you both high quality reverbs and compression (either single or multiband), and will allow you to stay all digital if you want to.
Or buy the Mangler for the compression and the other effects, and get a TC M300 for reverbs, or TC M-One.