Yes but there are four scenarios I can see here if I take this opportunity.
Best Case: I work here for 6 months and they decide to bring me on full time as an associate. Would look great on my b-school app, would be able to get LOR from my current engineering job as well as the PE firm. Work this job until I matriculate. Possible downside is that I'd be working at a boutique, unheard of firm and would be lumped in with applicants from top PE firms in the applicant pool.
Second Best Case: Work here for 6 months and use it to find a position elsewhere in PE full time. Would look okay on my b-school app, would be able to get an LOR from my engineering job, possibly the internship, and possibly the new job. Same downsides as above.
Second Worst Case Scenario: Work here for 6 months and use it to find a position in a similar field but not PE, such as at a mezz debt shop or something. Would look awkward on my application and I would have trouble explaining my story. Same LOR's as above.
Worst Case Scenario: Work here for 6 months, can't find anything in the field or a related field. Can't get a job at the firm, either. Have to go back to engineering. Can get LOR's from my current engineering job and the internship but not the new company. My resume looks very awkward and makes telling my story very difficult. Lumped in with PE applicants or engineering consultants, depending on how I try to spin my resume.
So the worst case scenario, which is also the most likely, is what I'm concerned about the most, but the other cases have challenges of their own. How do I deal with these issues?