For the past 12 months, I did an experiment and added a BIN price to 4500 domains.
Over the year, 27 domains sold, an average of 0.6%. The average sales price was around $1450.
Ratio was: initial investment (cost of domains) x 4.36 = profit (after taking off commissions and registration costs) - which was excellent, despite the low sales %.
Over 3 months, I did the same experiment with another set of 1050 domains (BIN priced them all).
3 domains sold over the 3 month period, an average of around 1.35%. The average sales price was around €1350.
Ratio: initial investment (cost of domains) x 3.92 = profit (after taking off commissions and registration costs).
Starting April 2018, I switched strategies and adding "make offer" with a min £200/$200/€200 to all pages.
Results after one (group of 9500 domains that cost just £9500, promo price):
11 sales in April ( = yearly average: 1.4%). Average sale around $921.
Formula: initial investment (cost of domains) x 7 = profit
Also applied the "make offer" strategy to another group of 3135 domains (€9400 cost). Results:
4 sales in April ( = yearly average: 1.53%). Average sale around €1175.
Formula: initial investment (cost of domains) x 4.08 = profit
Results, offers can vary depending on season, quality of domains etc. However it seems that "make offer" can actually result in selling slightly more names/year. I believe that more buyers can be turned away by higher-than-budget BINs, than buyers that would be turned away (see a listing and not make an offer at all) be seeing "make offer" rather than a BIN price.
With a reasonable min offer, you can attract offers from buyers that do not have the typical sweet spot budget ($x,xxx to mid $x,xxx); several mid to high $xxx sales add up fast.
"Make offer" also gives you the opportunity to extract max. value for a majority of sales, as upon receiving interest/an offer, you can research the buyer, the popularity/potential brand value of the domain you are selling (checking out tech/hot terms; a domain could overnight gain more in-demand/value-enhancing characteristics).
BIN-pricing the entire portfolio is great for mass-selling in the sweet-spot with ease. That is why NameFind, HugeDomains.com are set up that way; it streamlines the process with as little friction as possible; no negotiations, almost everything is automated - and so it should be when we are talking millions of domains under MGMT.
However, with regards to portfolios comprising of 5000-100,000 domains, I think the ideal strategy, in most cases would be to combine both models, but placing emphases on the "make offer" set up. This would be done by BIN pricing around 25-30% of the portfolio (obviously not including any ultra-premiums in that mix) and leaving the majority with "make offer". This could ensure that you would extract max. value from the majority of the portfolio, whilst leaving a portion on auto-sell.
This feedback is simply based on my past experience (past 3-12 months) and the models, to a great extent, have produced successful results across the board.