I'm not aware of anything in OpenBSD that looks at QoS, but I'm not totally
familiar with this area myself.

That said, I have a dual stack gateway/router/firewall that does use altq,
which in turn prioritizes traffic (I'm using `priq'):

# Priority Queueing Outbound
altq on $ext_if priq bandwidth  200Kb \
        queue { evoip_pri evoip essh_pri essh email edef_pri edef }
queue evoip_pri priority 7
queue evoip     priority 6
queue essh_pri  priority 5
queue essh      priority 4
queue email     priority 3
queue edef_pri  priority 2
queue edef      priority 1 priq(default)

# Priority Queueing Inbound
altq on $int_if priq bandwidth  200Kb \
        queue { ivoip_pri ivoip issh_pri issh idef_pri idef }
queue ivoip_pri priority 6
queue ivoip     priority 5
queue issh_pri  priority 4
queue issh      priority 3
queue idef_pri  priority 2
queue idef      priority 1 priq(default)

Then later I have rules that ultimately expand into things like:

root:6# pfctl -sr | grep ssh
pass in on we1 inet proto tcp from any to any port = ssh
pass in on we1 proto tcp from any port = ssh to any keep state queue(essh_pri, essh)
pass in on gif0 proto tcp from any port = ssh to any keep state queue(essh_pri, essh)
pass out on we1 proto tcp from any to any port = ssh keep state queue(essh_pri, essh)
pass out on gif0 proto tcp from any to any port = ssh keep state queue(essh_pri, essh)
pass in on ne3 proto tcp from any port = ssh to any keep state queue(issh_pri, issh)
pass out on ne3 proto tcp from any to any port = ssh keep state queue(issh_pri, issh)
root:7# 

So both v4 and v6 ssh connections get queued at the proper priority.

This probably doesn't help, but this is what I do.
-- 
Todd Fries .. todd@fries.net

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Penned by Mischa Diehm on Fri, Aug 13, 2004 at 12:23:56PM +0200, we have:
| Is that a "no we don't use it" or a "this has been answered a
| million times"  silence? Since I can't find any answers in the archives
| it must be the first ;)
| 
| Oh well ...
| 
|     Mischa 
| 
| -- 
| "Mit seinem Geld begnuegt sich keiner, mit seinem Verstand jeder."
|  (Quelle: Unbekannt)