YES. If you have a manager who is great at sale then by all means make sure they do it - but then consider the time it takes to do this.
As I have been onsite for 6 months running a major turnaround park, I can tell you this takes A LOT of time to do this!! Also, you need to assess what your manager's strengths and weaknesses are. Typically, good operational managers are not good salespeople.
We have several parks with lots of hispanics. We hired a great VA for Mexico who takes all our calls and does all the initial sales and pre-screening. It has really helped our sales process.
of course this adds an additional layer to our process which can be a negative but considering all the 'Crap' calls we get this has allowed managers to do all the other tasks they need to.
PS: This only makes sense if you have a lot of homes to sell. If sales is a very small % of your overall operations then this model does not make sense. You need to assess the role of sale and time of sale to the overall time commitments required.