I don't like the idea at all. I don't know why Relic thought this would be a positive change. I noticed this immediately in the trial and just had to scratch my head as to why this change was made. I hope Relic does't start doing this with other units.
I don't like not being able to mix up my shells midmatch. I feel like it takes away options. Honestly, the heavy mortars the best ones most of the time. In the alpha, I just used the light ones and the white phosphorous ones in certain situations. I'd never use them during 100% of the game. That just makes them useless as far as I'm concerned.
Those light HE mortar shells were awesome, less explosive damage but damn good range.