I've bought a pair of D-Li109 replacement on ebay, they worked well for a year. The only problem was I bought 7.2V batterys insted of the original 7.4V so it fooled the battery meter: it gone to red very quickly, but then it produced approxymatly the same number of images as the original pentax. Finally this tow battery get deformed. The pair was 5$, so it worst it.
Then I bought another tow, but now 7.4V. Currently I use this tow and the original and I am satisfied with all of them.
I have the battery adapter also, and 8 eneloop pro-s, but I use them in my Metz 44 flash only. The battery adapter is for emergency.