The updated timeline of the issue is as follows.
1. In the past, anyone with 485 pending had to use AP for traveling purpose. Using any visa including H/L indicates that they abandon their 485.
2. Then INS changed their policy to allow people on H/L to travel on H/L visa without jeopardizing their 485.
3. A 1997 INS memo allows H/L holder to travel on AP without terminating their orinal H/L privilege. (same policy as the current one ?)
4. In March, 2000. An INS memo was issued to change the policy: people traveling on AP terminated their original H/L staus.
5. On May 16, 2000. A new INS memo (the most recent one) reversed the previous memo. And this time H/Ls are given the maximum freedom. They can travel either on H/L visa or AP. Their working authorization, ability to extend within the US, ability to change to other status within the US, their 485 will not be adversely affected.