i also have been a tamiya junkie for quite awhile. but everytime i try to handbrush it, i get nasty streaks, and i always read about how great vallejos are. i bought mine from
www.ausfwerks.com and their prices are really great. i haven't tried them yet, but they look really nice. i also use pollyscale because i find that they have some colors that tamiya dosen't, like dust. also like someone already said, their airbrushable right out of the bottle. so from my limited experience, tamiya are great for base coats, and simple applications, when you want to get better tones and variations, switch over to pollyscale. then with the handpaintind parts, try the vallejo.