I have given up waiting for Cattlesoft to make a handheld version for Cattlemax. However I still use it on my own farm and the other herd I manage. The other herd is owned by a family with a few companies and they installed it on one of their server. I access it through a citrix client on either my laptop or my android. It basically brings up a computer screen like you are sitting at a computer where the server is. If you aren't already set up with a server, then it's probably the most expensive option.
What I did on my home system is installed an app on my phone called Xtralogic Remote Desktop
http://www.xtralogic.com/ I haven't used Go To My PC
http://www.gotomypc.com/ but that is an option by citrix. With these remote access systems you have to have your computer that cattlemax is installed on running.
If you keep your computer sleeping when not using it, you can use what's called Wake On LAN. You remotely send a signal to wake it up.
What I like about these is you are entering the data directly, you aren't messing around with syncing.
What I would prefer, and I think they are thinking about by one of their surveys is a web based version.
The other option I haven't explored is to have it installed on a cloud service.