Where does CorpDev/Corp M&A comp max out?

I don't think you are too far off, if you look at CGOs (who are essentially board level M&A Reps) Their annual comp tends to come out to 800K-1.5M which is right in the ball park of your guess. 

Industry matters. So does company size. 
 

1x cash comp and 1x RSU comp is well below VP Corp Dev pay for F100 

ignoring tech - most industries probably pay 1.3-1.5x cash bonus + 1.5x RSU (RSU is annual assuming flat comp across vesting)  for VP level

manager in corp dev in major cities should be $150k base 30% cash bonus and maybe stock + good 401k, etc. 

^^this is a pre Covid data point FYI

Throwing out a few datapoints for my midcap tech company:

1. My old boss (moved to a business leadership role) made 1M+ cash and i think a similar number in equity. He got in at the right time and had a pretty sweet deal.
2. My new boss makes I think 500K+ all in (10 year exp)
3. I make around 400k (7 year exp)

FWIW we do a lot more than M&A. I run our quarterly reporting process, we're involved in IR, FP&A, and do a lot of strategy work.

Sold a lot of business 300m to 2B.

VP level in the 1-2B range  are normally 500- 600 total cash plus 300 estimated equity value. 
 

most of the guys under 1B play 20% less with those under 400m not normally having any one higher then a sr. / manager making 250 all in.