H/S/W chances after 4 years PE, 2 years IB?

1. I am too far from the admissions game at this point to speak with certainty on four versus three. General advice would be that the more 'seasoned' the applicant, the more 'extra' stuff you have to point to. It makes sense intuitively, you've been around longer and enjoyed more time to be well-rounded. HBS is pretty explicit about their screening criteria: 'habit of leadership' and 'engaged community citizenship' are two of the three. 
   
   When I see people demean applicants from industries outside finance (or more frequently, diverse applicants) as being 'weaker' on-paper, one of the things I gently point out is that someone who can put a lot on paper to highlight their strengths on those two dimensions is literally answering the admissions prompt more fully than someone crushing it on the third ('analytical aptitude and appetite', which is usually an out of the park homer for a finance applicant). To keep the sports analogy going, two RBIs puts more points on the board than a solo homer.
   
   For the record, the finance applicants who are successful at HBS and GSB are invariably those who flex to score on at least one of the other two. For GSB, it really tends to be the latter. It's a 'change the world' vibe. It doesn't have to be ooey-gooey save the world, it can be very literal: I had this formative experience when I was young, have touched it in the following ways (high school leadership, college leadership, philanthropy or service as a young professional), and want to use the unique combination the school affords of X class, Y initiative, and Z student group to help me achieve ABC outcome in 123 timeframe. 
2. R1 and R2 have historically had acceptance rates within about five percentage points of each other. Your odds are pretty much the same in either round, it's just that the largest volume of applicants is seen in R1. 
   
   In terms of reapplicant success, people often get lost in the data when I think the real thing to focus on is what changed in your application. Going from a 740 to a 760 is not going to move the needle, so if you use the eight months to focus on your scores that won't be fruitful. If you're able to either reshape your non-professional elements (community leadership, references) or rewrite your application to highlight those that already existed, the eight months might yield a positive result.
   
   Some successful reapplicants do get there by leveling up. Going from a 680 to a 740, or taking two courses at a college to get As in quantitative subjects that were glaring errors on the undergrad transcript, for example. This is anecdotal, but I think more get there by realizing it's about showing more of the full picture of who they are. 
3. I am not here to knock on great schools that thousands of people would be happy to attend. At the same time, I do believe that for a high-performing individual in finance the value proposition outside of Harvard and Stanford is a toss-up and outside of HSW is net-negative.
   
   You won't be enjoying need-based scholarship, and unless you do something cataclysmic to make yourself a diamond applicant, you won't enjoy merit scholarships either. Paying out of pocket plus foregoing three-quarters of a million in income is a tough pill to swallow for anything other than the very best option. 

With regards to non HSW - I think it depends what I want to do after. If I decide PE isn't for me, I think one of those schools could make sense. I'm partially thinking about an MBA because I'm not sure this is the right career path for me long term (and its a lot easier to get out before locked up with unvested carry as VP).

This logic is poor in my view. If you're exploring other career paths, you want to maximize future optionality. You do that by being surrounded by the highest average caliber of professor, classmate, campus resources (entrepreneurship, social impact, government, and so on) and securing the best perception possible. 

Your option set is best maximized at the best school, put plainly. Plus you maintain the best optionality of continuing in finance but on a potentially more locally-optimized route: a fund that pays you more or works you less or is in a different industry or geography or all of the above.

So to recap:

• if you do choose to delay to apply in R1 next year, make sure you don't look unidimensional
• if you apply in R2 unsuccessfully, consider how to change your profile on the non-analytical dimensions
• don't think of going to a lower-ranked school to pursue things outside of finance; it's going to cost just as much and you'll get 'less'

Good luck man.