as soon as you start wandering outside, the possibilities are limitless. just like the risks to be disappointed.
while I can clearly see why H2O would suggest the R50 as a close alternative, the hf5 don't sound anything like a B2. do you EQ your IEM? is there something in the B2's sound you could do without?
there might be plenty of IEMs you would prefer to the B2/dba02(same thing), but it's always hard to know how you would feel about a different signature, different insertion depth(etymotic can do the double trick of being small yet uncomfortable to many) or simply something bigger. there are also a few nice sounding IEMs that are vented and have super poor isolation, so that's another decision to make.
personally I really dislike the signature of the B2, but my tastes are mine only. if you do enjoy the B2 overall, in your stead I would probably just grab another pair. I sure wish I could find the sound I love in such a small IEM.
"don't change a winning team", but only you know if you were winning with the B2. ^_^