I don't use a bass amp as I get the sound I need from my pedalboard, but on the board i most definitely use fx loops. Two types of loops; 'aby' loopers and a 3 channel switchable parallel mixer pedal. The aby just switches in a send & return loop, no gain or phase but does have the ability to have channel A, channel B or both.
The trimixer is a different deal, up to 3 channels in parallel. The main benefit for me with this is the ability to control the send and return gain and phase. I've got some pedals which are easy to overload the input, but with the trimixer I can control the gain structure and make sure it's not too hot a signal, and likewise on the return.
FX loops definitely helps you keep your signal under control.