Yes, I bought rims and tyres from D4x4, and they offered to stick the beads in when they fitted them up.
So... balancing....? Very very good, virtually no wheel wobble at all even up to 90mph on a private runway That is 33x10.5x16s Simex JT2s on 16x8 steel mods.
One bad experience, soon after fitting them, I went off road and aired the tyres down to about 15 PSI, then all 4 of the valves started leaking air quite quickly, I assumed a bad batch of valves and found a local garage willing to sell me 4 new valves and I set about swapping them , it was at this point that the reason for the leak was one or more of the beads getting stuck behind the valve and stopping it from closing.
So... if you air your tyres down often, you may want to look at using larger ceramic BBs rather than the balancing beads D4x4 supply.