First, let me congratulate you on taking game at that distance with the 1322! Is yours modded much? As far as the accuracy of the Discovery vs the 392, it's probably a toss up. The 392s often have paint overspray in the barrel crown which can affect accuracy(I seem to remember reading about folks using carburetor cleaner and a Q-tip to clean it out), triggers can be improved as well. Scope mounting is a bit awkward on the 392, though Greg Lundy at Ballistic Enterprises has designed a very solid scope mount for it (I think RL airguns carries it). You could also mount a peep sight. The 392 has the virtue of being self contained, all you need is pellets and elbow grease. The Discovery will get you more power than the 392, but will require a hand pump or scuba tank and fill adapter which adds to the cost. The trigger can be modded or replaced with a Marauder trigger group which is an excellent trigger. The Discovery can suffer from poi shifts as the breech isn't secured to the airtube all that well, many add a second barrel band to fix this(though it made things worse on mine). As in all things, you make up your own mind, it sounds like the multi-pump is working great for you, but you might want to explore the world of PCPs.
John