Carbon or aluminum seatpost

[Digi]

One of my carbon seatposts fractured when I ran over a bump on the road.  Anyone else have problems with your carbon seatposts?  I was thinking about going aluminum.  Also what about seatpost length?  My 29er MTB has a 350mm post on it now but its almost maxed out (at the .5cm mark) and I'm afraid it's going to damage my frame on a big hit.

[RS VR6]

You can try a longer post if you're maxing it out. I'm running a Syntace P6 HiFlex...best carbon post evar. As long as you don't go beyond the minimum insertion line...the frame should be ok. You typically want the bottom of the seat post to be inserted past the top tube.

[Digi]

It seems to me that the minimum insertion is walking a thing line.  With all the leverage from the seatpost, I would imagine it could fracture the frame.  To me, a safe distance would be at least 1'"past the bottom of the top tube.

That seatpost you mentioned is friggin expensive!  What's so good about it?

[SportingGoods]

Carbon seatpost for MTB is so 2016!! 

Just kidding  I think you just have not been lucky. As mentioned, if you feel this is too close to the limit pick a longer seatpost. Then, seriously, I'll never use carbon seatpost on a MTB anymore. I use a RockShox Reverb as this is the best upgrade to a MTB.

Then, I still use a Carbon seatpost on my road bike and this is fine (a generic one). I don't land like a fat cow on my saddle, I lift my ass over bumps, for my comfort more then for my seatpost though 

So, just go for it

[RS VR6]

That seatpost you mentioned is friggin expensive!  What's so good about it?

It flexes a decent amount and makes the unexpected large lumps in the trail hurt a bit less. I also had a Specialized CG-R post and the P6 feels just as good without the goofy look and ridiculous amount of setback.

[carbonazza]

I put carbon PROCRAFT seatposts on all my bikes( their AL stems too ).

The 27.2mm version flexes well and is comfortable.
And it is very light for its price.

But at 67kg, I may not be a good longevity/strength test rider.