Whilst I do very much like Cumaru as an alternative timber for Decking I do see limitations for its use in the UK.
Most contractors think they know best as assume all timber for decking is equal… we know that it isn’t. When using Cumaru as decking in the UK because we go from soaking wet to bone dry and of course plus 40 Deg C to -15 deg C we suffer from massive expansion and contraction issues.
Due to these climatic conditions I recommend only using Cumaru at 28 or 36mm thickness when used as hardwood decking – I also recommend a minimum of C25 and in section of 150 x 47 as structure. I also would insist on max centres of 500 and using predrilled and countersunk holes for fixing with 75mm screws, stainless of course. Anything less and your timber will move and snap the heads off… pretty much the same as Bankira (Yellow Balau).
Sanded or treated with Owatrol Prepdeck, NeTtrol and then soaked in either D1 or Textrol Exterior decking oil.
Do the compared to Teak or Ipe I would say, No, Cumaru is not the best decking material.