I use a Garmin GPSMAP 64s and Ian does the wizardry to convert the data file into a graph for his website. The 64s is a mid range recorder using both GPS and GLONASS satellites for improved accuracy. It also has a barometric altimeter for elevation; this has some downsides but is very good at identifying small changes in height (summits). The display(s) can be configured to suit your requirements whilst it can be set to record in intervals by distance or time. At first I used distance (0.1 mile) - better resolution than 1/4 mileposts and not too many data points (S&C gave 750-800 points). This method was a bit cumbersome so for easier and more detailed analysis I switched to time interval. You can set to record every second but then on say a 2 hour leg you would have 7000+ data points. I have compromised on a 4 second interval; this is sufficiently accurate (with interpolation where necessary) for my purposes and limits the number of points to around 2000-3000 for a typical leg. The data files (GPX) can be downloaded for viewing/processing. Most software is aimed at cyclists/runners but several are available including Garmin's own software (I'm not a fan), Strava (that Ian uses); both draw graphs. I use either GPS Track Editor (downloadable) or Javawa Track Analyser (web based), both free. Both convert the files and overlay them on maps with data available for perusal. The main benefit of information taken from data is that "rogue" points are easily identified, not always the case with spot readings. Hope this helps, if you need any further info perhaps a PM may be better to avoid the dreaded thread drift and avoid boring the world and his wife.