"[O]ne wonders whether the Sun Capital decision could ultimately have broader implications in the world of employee benefits and executive compensation, where the controlled group rules arise in many contexts. If a private equity fund and one or more of its portfolio companies can be treated as a controlled group (and, therefore, as a single employer) under the 'investment plus' standard of Sun Capital, the constituent entities could experience a number of undesirable consequences: [1] The retirement plans maintained by the controlled group members would be subject to coverage and nondiscrimination testing based on the entire combined workforce of the fund and the portfolio companies; [2] There would be joint and several liability for any defined benefit pension plan unfunded benefit obligations (not just for multiemployer plans); [3] Employees who move from one portfolio company to another may not be considered to have separated from service in a way that would trigger the right to receive benefit payments; [and] [4] The employers would have to be combined for purposes of applying the employer shared responsibility requirements of the Affordable Care Act (a/k/a the play or pay mandate)." [Sun Capital Partners III, L.P. v. New England Teamsters & Trucking Ind. Pension Fund, No. 12-2312 (1st Cir. July 24, 2013)]