I recommend keeping a CLOSE EYE on DASH/USD rather than DASH/BTC. WHY? To protect your USD Capital. Not sure if your oder would be filled in DASH/USD if there was a flash crash. You would have to sell large orders in DASH/BTC. However, if DASH/USD is crashing, BTCUSD has already done so beforehand or it is a sign it's about to.
If you are not as concerned about your USD Capital and are willing to simply accumulate more BTC to store for future value; then by all means, trade DASH in BTC's.