The tanks available from HL in 1/16 scale are:

Tiger I
M26 Pershing
Panther
Walker Bulldog (latest release)

These come in various guises; standard (basic model), smoke & sound, and those upgraded to be "Super" versions with metal gearboxes, metal tracks, etc.
All of these come with multifunction two-stick transmitters with interchangeable crystals and the smoke & sound have proportional speed control.

The T-34 is from another manufacturer/conglomerate known as WSN/Trumpeter: http://www.tankzone.co.uk/cart/trumpeter_16.htm

There has not been any noted change to the 1/24 scale series of which you speak (Leo/Abrams). Those, to my knowledge, still retain the old pushbutton controllers with a stepped speed control (one button is fast, another is faster, etc.).

-H