If the goblin's right in front of us, requiring immediate action, then of course you transition to the handgun and let him have a few. If there is no immediate threat, my shotgun always has a sling so just sling her on my back and draw the Glock.
Now as to the question as to do you "drop or retain the shotgun", I don't see any reason to drop the shotgun, regardless of the goblin's proximity. Transitioning to handgun does not require you to drop your shotgun. If you have a conventional (or no) sling, you just bring your shotgun to your body with your non-dominant hand, muzzle pointed up, with the forearm against your non-dominant pectoral muscle. Your dominant hand draws the handgun.
If you have a Giles or similar tactical sling, you go for your handgun with your dominant hand and bring the forearm dowm with your non-dominant hand in a controlled fall type fashion. You don't want to let it go and have gravity do all the work -- it's very easy to get socked in a delicate place if you let the forearm free-fall. You can then use both hands to fire the handgun.
Justin
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Justin T. Huang, Esq.
late of Kennett Square, Pennsylvania
[This message has been edited by jthuang (edited July 25, 2000).]