Have fun and post a report! Hoping to get back there in August. I haven't fished the Animas since my first days of fly fishing, which combined w/ several other beginner errors and a 11am - 3pm time window didn't bring about any fish encounters. I was also probably still reeling the entire line back in at the time so that didn't help either.
It depends on where you're fishing, but the biggest challenge for me when i started fishing more out West was casting distance using 4-6wts and tiny flies. rarely cast my trout setups more than 30-45 feet here, often much less, but with the bigger water, unless you're drifting, you're going to want to be able to sling it out and still get a good lie. field practice, or even taking your trout setup to the potomac might be worth the effort just to get your distance up a bit. if you wade, be careful and consider bringing a thicker layer to line your waders! mostly super cold snow melt this time of year.