Guys here is my experience. Sorry for any typos.
1st Online TRV applied in Jan 2016 - rejected with reason not enough travel history
2nd Online TRV applied in Feb 2016 - rejected with reason 'doesn't proof she will return to India after trip of 1 month'
1st Online SOWP applied in Aug 2016 - rejected with reason 'not satisfied with relationship' (although I submitted all docs I did for adding her to PR, silly reason)
Late Aug 2016 - sent an email to Delhi HC explaining my case and requesting to reconsider
2nd Online SOWP applied on Sep 19 - attached following documents to explanation letter and also to application
Application forms, marriage certificate, her student certificates for graduation and showing she is skilled for a job, my BOWP, her passport copy naming me as a her husband, my job offer letter, customized employee verification letter from my employer with NOC code, my last 2 years tax returns, my last 4 pay stubs, my bank balance of 22k, bank statements for 4 months, my net worth in TFSA and RRSPs to prove I have enough funds to support her, my AOR for PR, her medical request letter from CIC and doctor's receipt for successful medical exam, a 2 page explanation letter highlighting my health issues and urgency of her coming here to support me, detailed reasons and explanations for her previous rejections etc...
I highly recommend applying for SOWP rather than TRV. Based on my experience on this forum, a better case and application for SOWP increases chances of approval. I can't stress enough to write a very detailed explanation letter. It took me 2 days to write this 2 page letter so please spend some time explaining your case.
May mercy be with you. Good luck. Also I don't check my personal messages often so apologies if I don't respond in timely fashion.