Pro's are quite obvious: allthough it varies per gun.
Most modern guns (pcp) only have shorter barrel and shorter cilinder
Some older guns also have other the ergonomics of the stock to suit youngsters etc (which are usually the focus of compact guns), with a short LOP, for instance the Tau 200 junior. The 200 jr ónly had an altered stock. Action and barrel length were exactly that of the Senior.
Some brands, allthough none excisting anymore in pcp-country afaik, lightened the whole gun, except only cutting the barrel and cilinder cheaply (like the Tau 7 jr). Grips may be thinner and smller in size.
I doubt the speed will decrease; you usually dont need much barrel length to achieve 7.5J, but its possible its a tad less. But as yr locktime decreases cause of shorter barrel, this is no problem. No problem anyway, cause speed is not important for 10m work (my Tay 7 match shoots only in the 120s).
Short cilinder/barrel: less front heavy, less total weight, less nr of shots, shorter line of sight, usually more recoil.
Accuracy wise, no difference, there are even examples where the compact is unexpected accurate (tau 7 junior)