[TYPO3-calendar] Upgrade from cal 1.7.0 to 1.10.3 ?

[Markus]

Hi,

I am still using an old version of cal. In the past I have several 
problems upgrading to newer versions of cal, that has sometimes broken 
my installation. So I am a little bit reserved to do cal upgrades...

A rollback to the old extension version is a little bit difficult, when 
there are great changes e.g. in the templating or database structures.

Are the changes between 1.7 and 1.10 very big so that the chance to run 
into problems is great?

Thanks,

Markus