TPS is a "hybrid" status , it does not affect the current status you are in , there is always + and - s , its part of life but having a back up here in USA is not bad and you wont have to regret after the December 2014, for that reason lots of F1 and with OPTs are applying for TPS , its a economic hard ship in the country for that reason it has been granted and predictions is that it will be renewed for some years at least few times for sure !!! so think properly and decide , the decision is definitely yours >>