Concurrent Reindex on Primary Key for large table

I have a large table with about 60 million rows, everyday I add 3-4 million,
remove 3-4 million and update 1-2 million. I have a script that reindexes
concurrently a couple of times a week, since I see significant bloat. I have
autovac on and the settings are below. I can't concurrently reindex the
primary key, since there can be only one on a table. I can't take the table
offline to do a drop/recreate. I assumed the autovac would take care of the
bloat there, but I checked the size of the index and dropped it and
recreated it and the size went from 2.5GB to 1.3GB and my daily import into
that table took almost half the time after recreating the primary key.
I was wondering what the options are to reindex it. Should i not have a
primary key and just a unique index so that I can concurrently reindex? Do I
lose anything by replacing the primary key with a unique index? I prefer to
have a primary key on the table for Slony, but I suppose I could make the
OID column the primary key just for SLONY purposes. 
Any thoughts about the best approach would be appreciated. Note that this
bloat on the primary key is from about 2-3 weeks of daily
deletes/updates/inserts. I have multiple tables with similar structure and
data size. 

Here are my autovac settings. I am on PostgreSQL 9.1.1

#autovacuum_max_workers = 3             # max number of autovacuum
subprocesses
#autovacuum_naptime = 1min              # time between autovacuum runs
autovacuum_vacuum_threshold =  20000    # min number of row updates before 
# vacuum default 50
autovacuum_analyze_threshold = 20000    # min number of row updates before  
# analyze default 50
autovacuum_vacuum_scale_factor = 0.1    # fraction of table size before
vacuum
autovacuum_analyze_scale_factor = 0.1   # fraction of table  size before
analyze
#autovacuum_freeze_max_age = 200000000  # maximum XID age before forced
vacuum
autovacuum_vacuum_cost_delay = 5ms    
#autovacuum_vacuum_cost_limit = -1  

Thanks
RV

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