I'd go pivotal if the seatposts were really as light as they could be. For now alienation is the only 30.9mm pivotal I've seen.my ride is on diet now .. made some research for seat on CRC site
it seems that DMR Squid 160gram plus any pivotal seatpost (alienation 333mm 30.0mm 232g)
all for dirty 40 this gonna replace my seat which weighs more that double
bmx stuffs can be used on DH, lol
If i ever find a long carbon pivotal seatpost, i would go mad!