I've heard a lot about the Janome 350E. There are a few differences that are cool like the threader (hope you get yours fixed) and the bobbin out signal but like you said yours and mine are pretty much the same. Make sure your dealer gets it working for you.
I've never stitched on denims and felt but that what you say is right.
My most favorite things to do are clocks and ornaments. I've only done a few onsies, a sweat shirt, three sweat pants, a t-shirt besides towels, dish cloths, baskets, aprons, hats, a card, and bookmarks.
Check out my embroidery and clock folders.
Write down all your questions to ask the dealer. I had a ton when I went for my three hour tour. LOL.