Probably some of the super knowledgeable folks will chime in at some point, but this is what's worked for me so far.
For planets, best imaging technique is going to be "lucky imaging", which involves taking video at high frame rates and short exposures in order to minimize the effects of atmospheric movement ("seeing"), and stacking the best few percent. I'm getting 185 fps from my ASI290 in a C11 with no barlow with a 400x400 pixel ROI and 4ms exposures. With my local seeing (best described as "meh") I might end up stacking 1-2% of 50,000+ frames before I start losing sharpness of fine details. If conditions are really good, I'll bump up to a 2x PowerMate. I don't know if you can specify an ROI for video on your cameras, nor what the maximum frame rate is. This is important for Jupiter in particular because the rapid rotation of the planet limits you to about 3-4 minutes of video before rotational movement become significant at usual imaging scales, and you have to use additional software like WinJuPos to "undo" the rotation. You might want to consider getting something like an ASI224MC or ASI290MC so that you can do this effectively.
With this technique, you want your pixel sampling to be fairly high, close to the theoretical limits for your aperture. Because the planets are fairly small, you can use small regions of interest (ROI) to increase the camera throughput. For Jupiter, (very) rough rule of thumb is to expect around 1 pixel per mm of aperture, so 115px across the disk for your scope. Or you can use Dawes Limit, or some have proposed 6-7 pixels across the theoretical Airy disk. If your seeing is really good, you could go higher, if it's not so good you might want to go lower. For example, with my setup and no barlow, I'm at 4.6 px/disk, a 2x puts me at 9.2 px/disk. I'll run through the numbers for your setup below.
Astronomy.tools is excellent for figuring out the numbers for your individual setup.
At 115mm aperture and 4.3 micron pixel pitch, your Dawes Limit (measure of theoretical resolving power, depends only on aperture) is 1.01 arcsec. At native focal length, your pixel scale with the T3i is 1.1 arcsec/px (depends on focal length and pixel size). You typically want pixel scale to be no larger than 1/2 of your Dawes Limit in order to adequately sample a feature of that size; this is known as the Nyquist criterion. So you would want at least a 2x barlow. That's just a minimum, higher such as 3-4x may certainly be usable depending on your seeing.
If we want to use the Airy disk criteria, the calculator at http://www.calctool....ptics/spot_size calculates a spot size of 9.4 microns (depends on f ratio only, but also wavelength of light - green is used as a middle of the road color), meaning that an infinitesimally small point of (green) light will produce a central spot no smaller than 9.4 microns on your sensor. So at native focal length and no barlow, you are at a little over 2 pixels per Airy disk (9.4 / 4.3). So a 3x barlow would get you to a reasonable sampling for average seeing.
If your seeing is excellent, you can use a barlow of higher power. If your seeing is not so good, you might want to go lower. A highly magnified image of a blurry planet is ... still blurry, just bigger.
Prime focus, always, for best image quality. You probably should use AutoStakkert for stacking, as it stacks small image segments based around alignment points, which yields a better result than stacking entire frames only. I like FireCapture for acquisition, although I don't if that will work with the Canon.
Hope this helps and makes some of the terminology a bit more understandable! Have fun!