No you shouldn't, rc6 is broken for delta cards.
Well, for now I don't have much of a choice, since the Delta 410 wasn't added before late December. So I cannot even use rc6 but must rely on recent CVS snapshots - which seem to often introduce as many bugs as they fix :-(
Anyway, I have a working driver ATM and if I run it with -rt I can use quite low audiobuf settings ( -15 works). The strange thing is, that I cannot notice the difference in using -audiobuf 15 100 or 1000. I have PD synced through netreceive to an OpenGL rendering of a firework explosion. The explosion triggers a 'bang' sample and I would expect a 1 second delay using an audiobuffer of 1000. However, the sound response is instant regardeless of the setting - but the 'DAC blocked' errors and audio clicks disappear.
I will be watching the ALSA dev list to see if the make improvements.
Cheers Soeren