After 15 years of 'experimental' ALTQ, the results are in. A new traffic shaping system, with fewer algorithms to choose from, has been introduced to replace the expermental code.
The first part of the new system, always-on priorities (see http://home.nuug.no/~peter/pf/newest/prio.html, was introduced in OpenBSD 5.5.
The rest of the new queue system debuts in OpenBSD 5.5. ALTQ has already been removed in what will be OpenBSD 5.6. There is no way back.
During the grace period, there is one simple trick you can use until you take the plunge: The oldqueue trick.