I select the "maximize revenue with AdSense" option, basically have AdSense compete with the DFP line items via dynamic allocation. You get better yields vs. just pasting the AdSense tags as a separate line item since you have to set a fixed CPM for line items.
Yes it is worthwhile, there is a learning curve involved with the process. I personally would not do it unless one makes at least 10k+ per year. You may or may not see positives. Without proper setup and strategy going in, you can actually see decreased earning / negatives. (Due to many moving parts that can go wrong, codes, setup, bids, etc). I personally do not use it for my relatively smaller sites. Personally speaking, I first tried out DFP 5~6 years ago after going to a local "learn with adsense" meeting, I did very poorly with DFP at that time. I just "restarted" using it in beginning of Q4 of last year and loved my results. Size and experience matters. I am much more experienced now with a few more sites under my umbrella.
I'd recommend researching a lot into it, and just test it, it doesn't hurt to have knowledge in this area. Just don't put all of your inventory at once. Learn from the tests and implementation. You will one day eventually make use of it if you want to get to that next level (I don't know how big your sites are). Many levers / buttons can go wrong when you head into more complicated stuff like this. You can always outsource it, but the cost will usually outweigh the benefit unless you keep that outsource cost low. (But cheaper managers usually do a #*$!ty job which makes it even less worthwhile).
I do not find success using solo adsense only within dfp line items, I believe that it is best used with a couple more ad networks and rotate them with preset frequency caps. Your results may vary.
If anything, it looks like DFP is here to stay as the adserver winner. Many of its competitors appear to be dropping out of the space, or end up working for Google's ecosystem instead.
They make it difficult however to use Adsense as a line item as it requires a special activation in your account that can only be done by someone working at Google, yet there are no ways (unsurprisingly) to contact them.
I use adsense and dfp on my sites, and have for a few years. I use dfp for my direct paid ads and fill with adsense in those slots. I use adsense directly as well, primarily for some responsive text ads. It is complicated and probably took me several months to get a semi-handle on it :)
Been using DFP on some spots for a longer time. Switchedback to direct adsense code. DFP is not what it used to be. DFP competing with Adsense is a thing of the past. Doesent really do it anymore unless you have 3rd party ads. Did not really notice a difference switching back to direct Adsense code. We have a few hundred thousand ad views per day.
DFP is good to collapse white space. Harder to work with responsive ads. It is an ad serving platform. Not a market. Unless you have 3rd party netoworks/ads I find it useless (unless if you want to collapsing white space).