Not sure about the TBS system but people are working on a compatible battle system as we speak which will include a lot more tankers to join in the fun
As for the difference in Tamiya and HLs of course the tamiyas are dearer due to build quality and parts would last alot longer as a HL owner for only a month ive been through a few parts already but like you said many people get into rc tanks by buying the cheaper options then upgrading to dearer kite ie Tamiya
Put it this way if my HL tiger had a head on with a Tamiya tiger i know which one id put my money on surviving lol