Gen6 Camry - Viper Remote Start install, bypass question

[money042]

I picked up a Viper 5701 unit at a nice price. I then needed to get a bypass for the car's immobilizer. I picked up the XK05. After digging around and planning the install, the wires of XK05 needs to be connected to the ECM connector, which is located in the engine bay. I feel this is a pain in the butt and want to avoid going thru the firewall (I plan to install the alarm siren inside the cabin. Blow the crooks eardrums out if he attempts drives off in the car ). I then started to look for other options. Directed also offers a PKALL. This is wired to connectors in the steering column which seems much easier to install. My questions are,
1) Is there big differences between the XK05 and the PKALL?
2) Why would Directed offer two units if they both do the same thing?

Thanks for the help.

edit: Sorry, my bad, i put this in the wrong forum. Admins, please move this to the Audio, Video, and Security forum. Thx!