Reply Manager WAS one of the best systems we used, however since takeover by XSellco and migration to their version of the system it is without doubt now the worst system we have ..
The migration was forced with the promise that *everything will be migrated* Nothing could have been further from the truth.
One of the main issues for us is the old version was very folder based and we could segregate messages into channel folders, this no longer works the same way (we have always found it is easier to deal with each channel at the same time) There are folders in the new version, although message filtering does not work, so we cannot use this way. We had a major issue with messages that had been responded to re-appearing in the *needs action* view, countless error messages and niggles.
The change has left us in a mess at the start of the busiest quarter of the year.
They seem to be blaming Ebay for API issues and the integration with Linnworks is now virtually non existent.
Additionally their support is very poor offering contradictory responses and answers. Incredibly their own ticketing system to deal with support has no threading / titles or ticket numbers, so you often receive generic / vague answers (we fixed that .. ) to tickets and have no clue as to what the original issue was !