Judging from reviews, both cards require about the same power under load (the 970 actually needs a few Watt less even). The VGA upgrade is not a reason to upgrade your PSU, if everything was running fine before.
Regarding your other concerns: Any power supply has the chance to take some components with it if it is malfunctioning. However, that is not the rule and the TR2 is not known for having more RMA cases than other power supplies. The forum posts you found were probably individual cases that you can find for pretty much any power supply on the market. Did you know that the TR2 has over current protection, over voltage protection, under voltage protection, over power protection and short circuit protection? I can not promise you with a 100% certainty that those protection circuits will always kick in to protect your hardware but that is their purpose and it works most of the time.