Agree with the ARC500 choice. You will need a Premium Membership with RR to access the database. I have a Pro 106 (RS version of the PSR 500) purchased the year it was introduced, and it still works great.
To each his own. I agree with you concerning the recommendation, Win500. For me, ARC was user-unfriendly. I hated it. I threw it in the trash.
With Win500, you can deal with more visual fields that are more helpful. With ARC, you cannot see the radio parameters and talk groups on one screen like Win500. It is a bit different.
ARC500 does have a user guide in our wiki (the link is at the bottom); unfortunately the wiki site that had the Win500 user guide is down. And don't forget the Easier to Read manual, which is also linked in the above...Mike