Agree with durhamlad - unless this is an unusual company, it won't be a PFIC. There are some individual companies that make their money by owning other companies, making most of the income and/or assets passive. Think a non-US version of Berkshire Hathaway, or any of the investment trusts and REITs. Maybe also some bank-type companies with a heavy focus on the investment side compared to retail/corporate banking, lending, etc. - that's where it gets fuzzy.
But if it's a "normal" company that makes and sells some kind of good or service as it's core business, you should be fine.
No harm in an ISA if you stick to those kind of individual companies either, but if you're going back to the US in 5-6 years, I'm inclined to agree it's not worth the hassle. You'd still have to do all the US reporting on dividends, any capital gains, etc. since the US doesn't recognize the ISA, and it only makes sense for long term buy-and-hold of those individual stocks.