LOL. mixin=0 is not supposed to be untraceable. It's just like a regular Bitcoin transaction.
Coming from you that gives me a a bit of increased confidence.
Won't increasing the mixin make your bloating problems even worse than they are now?
"Bloating problems" implies that the usage is wasteful which it is not given the goal of private transactions. The same applies to darksend transactions, especially given the use of denominations (same as Monero; in fact with a higher "bloating" factor in general since fewer denominations are allowed), with multiple rounds being done (not needed in Monero), or even just the network traffic of talking to masternodes to set up the darksends. None of it is cost-free but the cost is being incurred to accomplish a purpose, not waste.
I mean we have Monero full node running on a Raspberry Pi at this point (experimental build still) so I think its pretty silly to go on and on about bloat.
From what I read, it seems like you are under the impression that Darksend rounds happen on the Dash Blockchain, this is a misconception.
I'm basing my understanding on this: http://cdn.anonymousbitcoinbook.com/darkcoin/darksend-paper/Atlas_Darksend-Analysis-v001.pdf
...
A randomly-selected Masternode orchestrates the signing of the transaction between the peers. On the blockchain, this type of transaction resembles several individual Bitcoin transactions “pasted” together into a single Darkcoin transaction.