Multi-member files - Big picture feedback

Pete,

It sort of depends if you care to have your design be to the old
S/38-AS/400-traditional iSeries- System i5 file architecture, or if you
wish to design your application using industry standard, modern,
Relational DBMS architecture as found in the top RDBMs systems (the real
DB2, & ORACLE).   If the former, then it doesn't matter, use whatever
you wish.  

If the latter, you have to make the mental transition from the old way
to the new using only SQL commands and functions, all the way from
CREATE COLLECTION/SCHEMA on down.   Even IBM is trying to move its
System i5 folks to this paradigm so it can compete, over the LONG haul. 
 

IBM and its customers have been through this before, back in the '80s
on the mainframe (MVS & VM) where the died-in-the-wool programmers,
vendors, etc., said things like "VSAM forever" or "IMS is the only
robust DBMS",  "SQL is too slow", etc., etc., ad nauseum.   But, then
most made the change to the real DB2 and some were lost to ORACLE.   

But in either case, they moved to the industry standard RDBMS
architecture and SQL.   Hopefully, the majority of the System i5 world
will as well.   Otherwise, I fear for its long term survival.   
Also, having good experience with standard RDBMS architecture and SQL
is good for your resume regardless of platform.

Later,

Dave