Thanks for the kind words guys! Ok so I'm not going to comment on brand vs brand, I think honestly these guys on the forum can explain just as good if not better than myself and most aren't biased. I will however comment on the IR side of things and my preferences...
I like a metal chassis tank personally but with as much plastic as possible except for the gearboxes. For the gearboxes I only run our new steel variants (and yes, they will fit on some other models just in case you need to upgrade another brand, though Tamiya is a bit more work than others) and for the drivetrain I run metal sprockets and idlers. The tracks and road wheels I keep plastic to save on weight. This is going to be your best bet for a PURE infrared battle tank and I'm sure most here will agree with the general setup no matter what brand it is.
I do occasionally run my metal edition tanks for battle and my Tiger 1 is over 20lbs and has larger motors, aftermarket control board, and as much metal as I can slap on it. It is also very customized on the inside and looks nothing like most other tanks internally, but to each his own. The lighter the tank the quicker the response you will get but this is also heavily dependent on your motors/drivetrain/motherboard as well. With enough power or something like a Sabertooth then 20lbs is nothing to push.
We do have a Tiger 1 kit as well if you like to build, it can save you a decent amount of money while providing you with the knowledge of the model itself while not killing the wallet (or making the wife/gf hate your hobby from the start). This gives you the option to run whatever electronics you like whether it be ours or something like the IBU or Clark boards. If you are a RTR type of guy then as stated above there are lots of options from multiple brands in multiple price levels. Either way you go you will most always have plenty of support from this forum as there are a lot of seasoned tankers here with many years of experience.