I think only a very limited number of people can answer this one (namely cafe22) as I am not one of them who have experience with a GS3 etc. On the other hand, I've always personally approached it as a question of at what point is the upgrade to let's say a GS3 simply for marginal gains and a point of diminishing returns. Others may view it differently but after 10+ years of home use, I found chasing after unicorn shots so exhausting so I just enjoy it to the best of my abilities as-is.
Based on coffee zealot / real-world reviews of the Rocket Epica, I would recommend waiting until version 2 on onward are launched as the original version has a laundry list of issues due to electronics. It's possible they've already corrected the issues on them, so I could very well be wrong. The same applies to Slayers - they are a PITA for reliability and repairs. I wouldn't even know who would help you in Vancouver for them.