So I bought a new 4RU rack recently, Stagg, not to expensive $200AUD. So it's nice and simple, MP-2, Alesis Midiverb4 in the MP-2 fx loop, B200s. I did have this stuff in another 4RU rack I had but the rack was as heavy as the gear (plywood rack with all heavy duty road case fittings and huge). So I've always use a small mixer in my rig for fx send/return. This is basically the first time I've used the MP-2 loop. So one tip I'd offer is that the loop defaults to 25% mix when you switch it in. At first I was turning it down to 10% to balance with the Mv4. But I had to adjust each mix (a&b) on every patch as I want the fx in on all patches (faint short delay and reverb). So now instead I'm leaving the default 25% mix and turning down the Mv4 output to match.
Anyway the new rack is going well and allot more portable than my normal 8RU live rack or the heavy duty road case.