Tri N00b: Ironman North America Bike Course Elevation Comparison

I've been doing research to choose an Ironman course to race next year, but couldn't wrap my head around how the bike courses compared, so I decided to do a little plotting of the course elevation profiles (via Garmin .TCX files) I could find online. This is just me trying to get a relative understanding of how the courses compare in terms of elevation change, and is of course not the full story of how challenging the bike course is. Here are the results for a few North American IM bike courses (mostly the races I am interested in; ping me if you'd like me to provide another race).

The elevation change does not agree exactly with what IM provides in their Bike Elevation Maps (Fig 1), which could be attributed to a number of factors (including poor calibration in the barometric altimeter of the Garmin device, see Fig 3), however, I think that the relative comparison is what these figures are most useful for. For example, I have been wary of considering IM Coeur d'Alene as I thought the climbing was unlike anything I'd done, however, I found that the first climb at IMCdA is similar in elevation to a local hill (Swanton Rd.) that featured on IM 70.3 Santa Cruz, but Swanton is of steeper grade (Fig 2).

Fig 1: Ironman Bike Elevation Maps. Source: ironman.com

Fig 2: Hill comparison for IM Coeur d'Alene vs IM 70.3 Santa Cruz

I noticed some variation in elevation between different .tcx files on the same course (Fig 3). I wonder the effect on user data by not regularly updating 'known places' to help calibrate the unit? I have not performed this before, but will be interested in doing so on my next ride.