Tried another red much more famous cab sim. I returned it quite quickly not happy with it. Put the cabsim concept on the shelf for a couple of years then I found this... great unit. started using it with an old Marshall valve amp, put it between amp and cab and ran mic cable straight to mixer. Very nice, small tweek on the eq and ready to go without mics on cab. Later I needed a smaller rig so I got an old Digitech gsp21. Unfortunatly it didn´t work good enough straight to mixer but through this baby it worked quite well... so I bought another one to have me in stereo.
Some say it´s noisy, sure it do make noise but not noticable in a mix or in a noisy live event.
I have another rig today so my Ultra-G lays unused. Will keep them anyway just in case. Great unit.