Is it worth it getting Rebel T3i now?

Hi guys, local shops are doing discounts on the T3i now bundled with 18-55 IS II lens and 50/1.8 lens for less than 700$, which is good for us (VAT and stuff)

The T4i is priced at about 130 more with 18-55 IS II  and the SL1 is between the two, with the STM 18-55 lens.

From what I understand, the 600D has better IQ, but it's autofocus through the viewfinder is slower  and the liveview focus is much slower. It has an older sensor, but somewhat performs better.

Is the T4i worth the extra buck in terms of low light performance - mainly autofocus speed.

I really don't understand what is the difference in terms of AF speed and accuracy between the two.

I understand I loose the touchscreen, some processing speed and some nice movie stuff.

And finally - what about the SL1 - where does it stand? I mean - do I really need that articulating screen - if it were SL1 vs 600D - I guess not, as the AF on 600D live view is slow.

I see tha SL1 doesn't support remote flash control and it doesn't have an AF assist light, so you need to strobe. It aslo lacks the stereo microphone and has smaller battery.

I asked around and was recommended I get the newer T4i, as it has superior AF performance and is... well.... newer...

And last but not the least - I'm a advanced novice with good knowledge and not much skill. The camera will be used by my wife too and we'll be shooting mostly family photos while learning about photography. I'm planning to get the camera and a small compact TTL flash that can be rotated on both axes.