We currently ride a 30 chainring with 28 rear cog successfully with regular 15%+ grades. If the triple-to-double doesn't work out then a double will be on its way. House of Tandem seems to be doing this modification so my bet is that it will work. Stay tuned ...
The conversion from triple to double should work fine. There are a few minor issue that you should consider. Your current low gear is a 30 x 28. To get the equivalent gearing with a 52/36 crankset, you need a 40T cassette. The 40T cassette has bigger gear jumps, and will require the use of something like the Road Link (the Red derailleur has 32T capacity). A triple crankset may not have the ideal Q factor compared to a double crankset (eg. Lightning or daVinci).
These are all minor issue but worth some thought when you're splurging on eTap. You'll love the shifting!