Accepted an Offer for a Boutique, But then received an offer from a Tier 2 Firm

Throwaway account for obvious reasons. I have been working at a Boutique Life Sciences Firm for less than a year, it's a great firm in the Boston area (think Putnam, ClearView, Huron,, Clarion, Trinity Partners, etc.) and the work has been great. Out of the blue, however, a tier 2 firm (OW, Deloitte, LEK, S&) I interviewed with called me up and asked if I could start for them in October. As much as I like where I'm working now, plus the downside of having to move again, this firm does have much better placement into PE, which is where I'd like to end up eventually. The firm I'm at now has virtually no placement of alumni into PE. I just wanted to throw this situation out here and see what everyone thinks.