I see where you are coming from, but I am not sure that it would make sense as Sooloos uses its own metadata lookup service that has aggregated from a number of sources.
What do you store in this field, the Sooloos ID, the AMG/Rovi ID? The Sooloos ID would only be an internal lookup, so apart from confirming that Album A is exactly the same as Album A!, I cannot see a use for that. If it was the AMG/Rovi ID, that only makes sense if the metadata was sourced wholly from AMG/Rovi. But a lot of data on Sooloos is aggregated from a number of sources.
Only recently, I went through the metadata lookup process with a fellow HHer. They were trying to find where data from a certain album had been populated from as there were discrepancies with AMG. Using the AMG/Rovi API, which is more feature rich than the web pages, we looked up all the metadata for this album, yet we could not find where some of the information had been populated from nor conclusively confirm that it had actually been populated from AMG/Rovi. The conclusion was that this particular album was using data that either had not been sourced from AMG/Rovi or that it was aggregated data from a number of sources. I later confirmed with Meridian directly something that was initially said by them at the Sooloos HH2 'reveal', which was that Sooloos used its own metadata service.
Unfortunately, a proportion of this data is either stale, incomplete or invalid. However, Meridian are aware of this and hopefully are doing something about it.