A 1/4" hex chuck style is common for construction use which you need to drive a lot of screws and lag bolts. The bits can be swapped out quickly. With an adapter, like you mentioned, you can fit a typical socket onto the end.
I used one this way before I bought one with a 1/2" anvil. There are some negatives:
1) The adapters can be long and don't allow for the best access.
2) The adapters break since they are only 1/4". If you're planning on a big project, have a couple extra on hand.
3) They are not as powerful as a larger impact. This is idea for screwing into wood but not great for getting a bolt loose that's been rusted in for the last 20 years. They either won't get the bolt out, or they'll take many times longer (and put that much extra wear on your tools).
I have one of each for different types of work.
If you will be using an impact on sockets be sure to buy an impact set. They'll last longer and they won't shatter.
If you purchase an anvil style, you're going to want the hog ring style, not ball detent. Ball detent is for appications where you don't switch sockets often (aircraft) or absolutely can't drop a socket (nuclear).