Weighing and Communicating an offer

Hello, I've been working at a management consulting firm for almost a year, and one of my ex-directors offered me to come join his mc firm . It comes with a promotion from Analyst to Consultant and a significant raise (28% of base salary increase). However, I really enjoy working at my current firm, get along really well with my superiors, though that money is hard to pass up. My superiors at my present firm (unrelated to this offer) have told me that they are planning to promote me at the end of the FY in October which should (according to glassdoor) come with similar pay as the new offer. How do I handle this? Should I talk to them to see if my expectations are in line with reality? Decide in secret? All help is appreciated.