While this is a good analysis of PE vs VC investment styles, getting acquired by PE is more likely to be the result of a company’s performance, rather than its cause. An unprofitable VC-backed company IPO’ing in it’s 9th year is unlikely to get bought out by a PE firm. On the other hand Ping was 14 years old and had already started taking PE money in 2013.
Furthermore, the right question for to ask from a competitive perspective is not whether it is better or worse that your competitor was acquired by a PE fund than if it had received another round of VC, but whether their being acquired by a PE fund is better or worse than the alternatives that were open to it. It is hard to imagine that any VC fund was going to invest in a 14-year old company whose first venture round was 12 years ago.
In this particular case it looks like Ping was prepping for an IPO, so that was the most likely alternative. I have not seen as clear a comparison of the advantages and disadvantages of going public vs being acquired by a PE fund.