The Boss units are nice but sounds like overkill for what you need unless you want the amp models. *Here are my suggestions for your setup, remember, these are my opinions only:
Assuming that you are looking for time/modulation type effects, reverb, delay, chorus, etc..., you want to put these in your effects loop. *Boss pedals are great but they don't like line level (effects loop) levels. *Some loops have control over their level but I don't think the 5150 does. *I don't think the 505 would like line levels either. *You can get a rack mount unit, like the Lexicon MPX-100 for around $200 which is a killer unit for the price. *If you want to stay with pedals, the best pedal that I found to run in loops for this kind of stuff was an old Zoom 5050 Choir pedal. *It had really nice delays, reverb and chorus and it could handle line levels. *It also is programmable, meaning you could have 2 different programs and bypass, I loved mine. *I had a basic chorus/delay patch, another flange/delay patch for Pink Floyd's "Run" and U2's "God, pt 1"and bypass. *
Unfortunately they don't make these anymore so you'll have to find one used. *Part of what made me think about it is that I actually saw one for $50 at Robb's Music
in Boulder yesterday, and I think Rob at Spotlight Music
, has one for $75. *I almost bought one for myself, nostalgia probably. *The one at Robb's was a little beat but if it works WTH, don't know about the one at Spotlight but Rob is an honest guy, feel free to buy my Genz-Benz cabinet from him too
A hush pedal might not be a bad idea for the loop on a 5150 either.