Sounds like a cool thing to develop in excel using api too :-)... although I guess with historical data you are limited to large tile frames (day?)...so possibly not exactly what you need... (?)
Ps cool question! And I didn't know you could organise a bounty like this! Just knew about https://beta.cent.co :).
Ps There has been a Swedish study on this subject too. If worth it I can contact her (like I did earlier for another question) to ask what she used...
RE: Steem Bounty - Looking For a Website or Tool That Shows Price Movement over Time of Multiple Cryptos in 1 Graph