Re: What fly line to buy
Both Cortland, Scientific Anglers and Rio make excellent lines ... The reason for the different flavors is to try to satisfy the many appetites of fly fishers. You've already hit upon one of the reasons: your problem with line memory isn't a problem down south; in fact, few of us down in these waters would even consider throwing a line that would work perfectly for you.
You didn't mention the rod maker's name or the action, so I will assume it is a moderately fast graphite with fiberglass scrim.
In the cooler waters of the North, the Sci-Anglers GPX is a an excellent general purpose line; Cortland has one matching the GPX in their 555 and/or 444 lines ... The real issue, however, is what you want the line to do in fishing your waters. Frankly, I would recommend the Cortland's Sylk simple because you are not that far along in fly fishing. It has no memory at all and a composition that will feel good to you ... Since you do not have to worry about long casting, I would suggest a 5-weight, double-taper. It will easily give you 60-foot cast with almost anyone's rod. Don't for a minute believe that double-tapers are a thing of the past -- the are not!
If you have more information available, I will be happy to make a more specific response