Size and weight is a big decision factor when you are trying to find the ideal camera for your needs.
In this section, We are going to illustrate Canon 1100D and Canon SX30 IS side-by-side from the front, back and top in their relative dimensions. Canon 1100D has external dimensions of 130 x 100 x 78 mm (5.12 x 3.94 x 3.07″) and weighs 495 g (1.09 lb / 17.46 oz) (including batteries). Canon SX30 IS has external dimensions of 123 x 92 x 108 mm (4.84 x 3.62 x 4.25″) and weighs 601 g (1.32 lb / 21.20 oz) (including batteries).
Below you can see the front view size comparison of Canon 1100D and Canon SX30 IS. Canon SX30 IS is 7mm narrower and 8mm shorter than Canon 1100D but it is also 30mm thicker. As you can tell, actually this is not a fair size comparison since Canon SX30 IS has a built-in lens but Canon 1100D doesn't. Once you put a lens on 1100D, its thickness will increase significantly.
Weight is another important factor especially when deciding on a camera that you want to carry with you all day.
Canon 1100D is significantly lighter (106g ) than the Canon SX30 IS which may become a big advantage especially on long walking trips.
Again, this comparison may not be very useful in real life as we are comparing the weight of a camera with a built-in lens to the body-only weight of an interchangeable lens camera. Once you put a lens on 1100D, the total kit will weigh much higher.
Unfortunately neither Canon EOS 1100D (EOS Rebel T3 / EOS Kiss X50) nor Canon PowerShot SX30 IS provides any type of weather sealing in their body, so you have to give extra care especially when you are shooting outdoors. If weather sealing is a must-have feature for you, check these sections: Top DSLR Cameras with Weather Sealing Top Bridge Cameras with Weather Sealing
LCD Screen Size and Features
Canon 1100D and Canon SX30 IS's LCD screens has the same diagonal size of 2.7".
On the other hand, Canon SX30 IS sports a Fully Articulated screen
which you can change the angle and position of the screen almost freely, making it possible to shoot from waist or over the head levels, and especially very useful for shooting selfies and video. Canon 1100D's LCD screen is a fixed type which provides almost no flexibility in shooting positions compared to SX30 IS.