Thanks for posting this informative thread, AP
I'm a angelwork novice and have a lot to learn still. As you know I've started using the MBO's (with absolutely astonishing results) and addressed the angelic beings in very general terms, yet now I'm starting to feel a pull to invoke more specific energies for different issues. I'm excited to start experimenting with these and also curious to see if it will amplify the results of my requests.
So far I've found The Angel Bible by Hazel Raven informative and the one exercise I've tried very effective. It introduces the angelic hierarchies and angels or equivalents of different cultures, also angelwork with the kabala, crystals, colors, meditations, astrology, healing and even essential oils. It seems to cater for a very wide range of preferences. So far I am impressed