I use both yeast and baking powder in mine and I can't taste the yeast.
Being a home brewer, I have a distinct pallete that can taste a yeasty flavour from afar, and can tell differences of yeasts used in beers as each strain of yeast offers different flavours in the finished product.
I have used Tesco's bread yeast mostly, but last week I had ran out and used a good pinch of my Youngs wine yeast with no off flavours.
Next time I make a brew up I might try using a bit of the beer slurry for the yeast input and see how that fairs.