It's been almost 2 years since my post on this topic. I decided to use Printful for my printing and shipping service. So far, they have been very reliable. I frequently order "samples" that I review for quality and fit. I did a bunch recently since I had to switch my product line from American Apparel to another brand. I am planning on selling these samples locally at a fair or craft show.
My t-shirts start at $18.95 retail (base cost of the shirt is $13). I don't need to make windfall profits since I want to grow my brand. Printful has a nice integration into my Woocomerce site, customer service has been great, and I like the digital printing they provide. On top of that, they are opening more locations so it cuts down on shipping costs for my customers. Although they are a print on demand business, I can still have a stock created if I wanted to keep some on hand.
So far I have been delighted using their services. They're a nice upgrade from using a company like CafePress or Zazzle, where I can't have any interaction with my customers. Most importantly, I don't have to master a new skill of printing t-shirts. I just have to know what a good quality printer produces. I stay educated, but I can spend my time on my other skills.