Unsure. The behavior I observed with both the RP2 redstone wire on machines+CF blocks (but NOT on vanilla blocks or RP2 blocks) was that I could not place a switch (vanilla) or the wire against any of the IC2 blocks I tested (CF foam wall side, and machine side); at least the later of which worked in the last stable version. (In fact I noted /that/ by seeing the wire that had popped off my massfab when the wire pulsed and the blocks updated)
The reactor issue also allowed a 'shutdown' (forced off by redstone signal) reactor to blow up (I reloaded from the backup), and my failsafe vanilla switch on the side also failed to function (it popped off on block update, would not go back on even with shift click).
In all cases, failed items 'fell off' or the placement was rejected outright and returned to inventory. It briefly placed client-side. This is -likely- an issue with installing the dependencies -over- Forge; but the vanilla switch makes me not sure; hence the inclusion of the checksums for my files (md5) as well as the script I used to prepare the test jars.