It shouldn't but during installation you will be presented with a test page. If you get any errors then you stop and see what the error is about. Of course please backup everything first: both files and the database.
SMF needs to be updated if you are using versions 2.0.8 and 1.1.19 as security issues have been addressed:
SMF 2.1 Beta 1
SMF 2.1 Beta 1 has been released. Since this is Beta do not rush to put this in any live site. Personally, I usually wait many months after the official release because when it is considered stable and more people use its when even more bugs are found. Regardless these are the new features:
Comments: I see there is a new SMF release (2.0.9). And a BETA version also. How difficult is it to install an update? Does it have to be done from the CP or WHM panel?
2.0.9 was released awhile ago you should upgrade immediately via Admin if you can as it fixes security issues.
I suggest you should join my community to keep up to date with the latest.
I do not recommend installing the beta version until they have all the bugs worked out. Also installing that version will likely mean you will have to do over all mods and the theme.
SMF has been slow in making a fully responsive layout for their software and have chosen to do this as a means to answer Google's new policy about mobile responsiveness and their algorithm:
SMF 2.0.10/1.1.20 Released
SMF has released updates that should be applied as soon as possible. There was no indicator of vulnerabilities involved but take no chances. Those of you still using version 1 - please upgrade to version 2. Version 1 uses an older - soon to be defunct version of PHP.