My only advice..make sure your groomer knows what you are asking them to do,or if possible stay while its getting done.So you make sure it is what you want.
I don't have a problem with groomers,but some may be clueless or cut to much off.That would be my only issue.Some people just need really good decriptions.
If I went and picked up my dog,and the person says to me.."oh yea no problem,I know just what your looking for"..then I pick up my dog and he has been at the hands of a groomer that got scissor happy or clipper happy,the person would want to make sure they were ready for an a*** chewing.
I was quite intimidated about doing a shute the first time,and it may not have been perfect..but with all the explainations here,and folks are so willing to help,I just went and did it myself.Now I'm quite comfy doing it,even bottoms of the feet.
I know there are scads of vids on YouTube,about grooming shelties.I know there is an online seminar also that can be purchased,which I've heard has invaluable info.