Load test of new application - what to measure

Hello all!
I'd like to get some suggestions from experienced minds.

So we'v developed an application and our client will soon make a load test. Load test will be performed in a very real manner i.e. many users from many places will simulate their work for an hour. They'v already performed one such test but unfortunately without our notification so there aren't much results of the previous test, just according to their words "there are at least one operation that is slow in load test but isn't in 1-2
user environment".
Application has both OLTP and reporting parts, but tested will be only OLTP part. It is Web application with connection pooling. Load test will be performed on real data migrated from old app. It is 9.2.0.5. Oracle RAC (3 nodes with load balancing) on AIX. Tablespaces are locally managed with ASSM. Memory management is AUTO.
UNDO management is AUTO.

And the biggest question is - what to measure?

My plan till now is as follows:
1. Trace in previous time suspected operations. I.e. knowingly initiate them and trace all sessions until they complete (because we have connection pool and nobody knows to wich session what goes). 2. install statspack and at least take snapshots at the beginning and end. Unfortunately I haven't any experience with statspack (although I'v read supplied doco for it) and therefore I have two questions: What level do you suggest to use?
Is it worth to take a (few) snapshots in load time as well (remember duration will be ~1 hour)?
3. Take some statistics that statspack doesn't offer (at least I think so):
3.1. sequence numbers before and after test. 3.2. count table records before and after (especially I suspect some auditing information).
3.3. take snapshots of involved tables dba_segments before and after to see their possible growth.

Any comments, suggestions are welcome!

We would like to collect as much info as possible because next load test will be after a while and it would be nice to eliminate suspected performance problems as early as possible.

TIA!
Gints Plivna

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