It doesn't hurt to send some "feeler emails" to prospective profs. If they say that they are not able to write you a _strong_ recommendation, then go with the pro letters.
"The most effective letters of recommendation are written by ... with candor, detail, and objectivity. Letters that compare you to your ... not consider general, unreservedly praiseworthy letters helpful."**
... at least the minimum requisite letters of recommendation for a given ... - have everything else finished (application, letters of recommendations, all your transcripts ...
... at least the minimum requisite letters of recommendation for a given ... - have everything else finished (application, letters of recommendations, all your transcripts ...