Grout of pipe connector in manhole

[Sbortz]

Does anyone have a recommendation for grouting up the pipe protrusion into a concrete manhole? I have a relatively large trunk sewer (24" corrugated exterior/smooth wall HDPE pipe) connected to manholes with a standard flexible boot. Concrete manhole is a special design T-series base where the bench extends to the top of base. What are the benefits and negatives for directing my contractor to grout up around the entire circumference of the pipe invert inside of the manhole?

General specs of the situation:
-very flat slope on the pipe
-high ground water area
-bulk of the flow will be filtered from an industrial membrane system
-system empties into a pump station

 

[ccor]

I prefer the inside to be grouted. Flow is smoother and is less likely to trap debris and become an odor problem, although this probably isn't a concern here. I know some rubber boot manufacturers’ warranties are voided if the connection is grouted. Even so, we still have them grouted because the warranty on a rubber boot is worth so little.