The Doce Pares sticks don't have the full skin on them, so they'll get soft realitively quickly. I tended to get a couple of months out od then, if I was carefull and didn't do too much hard siniwali.
If you want to stick with rattan, your best bet is to find someone who brings the stuff in to make furniture. You can oftem buy a length (3 metres typically) for the price of a pair of "finished" sticks. you'll get 5 sticks out of this. You'll have to cut them to length and sand down the knickles, but you have a hardy stick.
There are a bunch of different kinds of rattan. We find manau rattan is a good mix of stregth and density, although it may be a bit heavier than you're used too.
Another way would be to use bahi, this is the centre of the coconut tree. It's heavier than rattan and hits harder, but it's still fibrous, so won't split like hardwood. If you use it, your partner will have to too, because it will probably eat the cane up.