When we got the first Pace sidemount (and chargecooler) setups someone on here (DaveG?) did a before/after test against the standard intercooler with the Sykes kit logging the intake temps.
The Pace side mount was found to be a small but worthwhile upgrade over the standard intercooler, at least with a standard turbo. Of course a front mount is a lot better, especially if you have a bigger turbo, or even a hybrid turbo.
The new uprated side mounts don't cost much less than a front mount so a bit pointless unless you can pick up a used one cheap (say under £100) and are sticking with the standard turbo, but if that's the case I'd say it's worthwhile as it would let you run a Gtec2 (with its more aggressive ignition advance) rather than just a Gtec1 if you have a 20vt.