[SSF] Members for tasks

Not what I mean: you're implementing a custom S3Represent here, and S3Represent does actually provide effective bulk representation out-of-the-box. 

But then inside the row-representation you're calling other S3Represents /per row/ - which effectively neutralizes the bulk-representation effect (therefore "counter-productive").

There is an elegant way to cascade bulk representation, see for example https://github.com/flavour/eden/blob/master/modules/s3db/project.py#L5688

The lookup_rows function there calls the /bulk/ method of the embedded representations (projects in this case), which stores the results in the respective S3Represent instance. That makes the subsequent lookups in represent_row just a dict lookup instead of one DB query per row (or even two like in your implementation).

The magic of S3Represents is that they "remember" all representations, so when you bulk-lookup once, and then subsequently call it for each individual value, it would just deliver from the local dict and not load from the db again.