MentalRay Animation

[isopropanol]

Hi guys...I am working at an animation for my company and i animated the logo and rendered with Max6 and MentalRay with GlobalIllumination (with the skylight only). The result is not what I did expect in terms of quality.The shadows are very dirty and in the last frames of the animation in the right bottom of the logo there are some shadows flickering. It tooks 2 min/frame approx to render it out. What I need to know what are the settings to experiment with to give shadows a better result? I tried tweeking the radius of the photons, the number of photons and the number of the samples but the result is ever the same. You can watch the movie here (4.5 mb MOV 2 sec approx.).

http://www.isoprop.net/Upload_Folder/SimulazioneUno.mov

Please watch it and give me your suggestion/opinion/help.

Do you think that Mentalray is the right choice in terms of money to render out animations with Global Illumination? Thanks all in advance..

Richard