While i can't say its does a better job than Suse, but most of the time it works. TBH i never trust those auto-resizing things. You are well better off customising it yourself.
I believe both of them use the same tools to achieve the result, only the graphical interface differs; I might be wrong, but I don't see any reason why it couldn't be. I've tried several distributions that do auto-resizing and all have worked; are you sure that you gave the amount of new free space (or new partition size) in the asked size, i.e. in MB if it asked so? If you think it's asking for MB instead of GB, you could very well give it the amount in MB - most probably it means that the same value in GBs would be too big for the harddisk anyway, so the installer would complain in that case -- the other way around this won't work, of course. (i.e. if you wanted to set the new free space to be 40GB, you could try giving 40000MB and if the installer really meant MBs, it'd be ok but if it really meant GBs, I'm pretty sure your HD is smaller than 40000GB so you'll just get an error; this way you can make sure if it asks for MBs or what).
Setting the partition sizes yourself is a good idea if you have a clear picture on how much space you need on the partitions, which partitions you need to have and so on..but if you're a rookie, it's no good to create a 20MB /root and a 90GB /boot, if the installer knows how to do the job.