I think it was the issues, but those could have been worked out, the major issue was what has happened to the term "mid range"
the lower end of the mid range has dipped below 200, and some of these markers like the e1 and some of Gog/SPs offerings are EP. The SLG just didn't have a market niche. If the quality was impossible to attain because the nature of a sear tripper is wrecked orings and random full auto (ask kinsman). And they can't offer it cheap enough to justify the problems or annoying sear tripping nature.
For UNDER 200 NEW you can get
GOG enmey (quality, slower, bullet proof, can become EP)
DP E1 (some quality issues, but EP)
GOG Envy (decent quality, EP, LP)
DP G4 (some issues, but way better performer, more potential)
Used Mini (nuff said)
2011 PMR (way better marker with true DYE quality)
then 250-300 becomes
NEW DP g5
So for the SAME price as the SLG there are several EP offerings with far fewer quality issues then the sear tripping SLG. I imagine Proto's profit margin was so slim they could not cut the price further.
The people the SLG appealed too (those looking for Proto's classic quality and a lower price) are more likely to throw the extra cash on a PMR or buy used higher ends. DP kinda does the SLG better, a marker with some quality issues but a lower price point and functionality of a higher end. THe DPs have similar price points, some issues with leaks, ect, but a MUCH higher end shot when they are working. just imo