Darkhorse has streamlined it pretty well lately. They used to take forever. Actually, the didn't do it for a long while, at first.
I like either way, If I'm able to hit the comic shop regularly I'll go with the single issues, but the TPBs are fine too. I do like the hunt on back issues as well. I don't display my comics on a shelf either, everything is in comic boxes with comic sleaves and a backercard. I've never had a beat up comic storing them this way.
Never would I buy both versions!
Another trouble with TPBs is the issues that DH will choose to include. Many are out of order. I just HAVE to have my comics in chronological order. DH also doesn't put every issue into TPBs and I've found a few TPBs where they don't state which issues are in it. I even emailed them to ask, they never responded.