Listnerds again. You have 
He asked this question to the audience on the latest Crypto Maniacs podcast, and I thought I'd check, but never got to it since I listened to the recording.
I believe the benefits provided by sharing your post on Listnerds are multiple, and can have a different impact from case to case.
This impact is obviously amplified the more clickthroughs you have. Since most emails have a CTR above 85%, it can be done little to improve on this end.
What you can do is send to more people. And maybe more often. What the platform can do is improve the open rates, and they are working on that.
An upgraded account matters (especially business or enterprise), because it helps you send to more people, more often. Enterprise also gives you one free solo mail per month (I think it's one, I have the business upgrade), and solo emails are automatically validated and sent to the ENTIRE userbase.
In my case, the highest influence Listnerds had was on the number of comments on my posts. That seems to be the case for most people who share posts on Listnerds, their own or of other authors.
The second metric that went up for me are the reblogs. Almost all my posts get reblogged, some of them multiple times. That is what usually creates the viral effect, so I'm very happy this happens and humbled and thankful to those who share my content.
Regarding upvotes, yes, I do receive additional upvotes that probably wouldn't have come if I hadn't been sharing my posts on Listnerds.
What we have to keep in mind is that many of the people on Listnerds have new Hive accounts or old and inactive ones for a long time. Thus the upvote value, in most cases, won't make a significant difference to a developed account.
It will have a more noticeable impact on small accounts, however.
At the same time, on the lookout for Hive posts shared on Listnerds are some big or even huge stakeholders. Either in HIVE or in other tokens.
For example, I do vote on enough of the Hive posts shared on Listnerds (especially if I catch them within their first 24 hours after publishing), and while I am not a whale, my stakes in multiple tokens gives a nice upvote to smaller accounts.
There are other people using Listnerds with higher stakes than mine who may vote on such posts or not.
Jon Olson is a two-times orca on HIVE and he also has important stakes in other tokens, and he does vote on probably all Hive posts shared on Listnerds. For now... while there aren't hundreds or thousands of them every day, lol.
Task is a LEO whale on the account he votes with on Leofinance (and has some HIVE POWER too). He keeps a close eye on content that is published on Leofinance, and he also pays attention to Listnerds from what I've seen. So, if you published content he deems worthy of an upvote, he will do it.
Of course, people on Hive should keep in mind that by sending emails on Listnerds which receive more than 20 upvotes, you get rewarded in another Hive-Engine token too (LISTNERDS) after 7 days. Add that to your author rewards for your posts, even though they are locked for 10 weeks on the Listnerds platform.
Overall, in my case I don't believe the author rewards boost are the main benefit for using Listnerds. In other people's cases, this could be the difference between receiving some author rewards and not receiving author rewards at all, because nobody finds your content and gives it a sizeable vote to be above the dust threshold (for new people: that's around $0.025 - if your rewards are lower than that, you will not receive author rewards on your post).