One Trick Pony or Dog of Many Tricks?

So I'm working my way through "The Writer's Guide to Selling Your Screenplay" by screenwriter/author, Cynthia Whitcomb, and I'm struggling with something in the book.

Q. If you're a beginning script writer is it better to write your screenplays in the same genre to show you have a depth of talent in that genre, or should you diversify and show a breadth of talent across all genres?

The case is made that it depends on where your interests lie. Cynthia states that if you're all about the comedy and that's what you love to write, then by all means, write comedy! And I totally agree. (whew, I'm sure Cynthia will be relieved!)

But my personal jones is to write in a variety of styles. Sure, my first two scripts have been action flicks, but that doesn't mean I don't think I can write a great comedy, or thriller, or sci-fi. But if I do, and I sit down with Agent Joe or Producer Bob, are they going to think I'm too flighty and not developed enough in any one area?

My hope is that my desire will be the neutralizing factor, as I firmly believe that I can write whatever genre I put my mind to. Comedy seems the toughest challenge, but I'll be happy to tackle it when the right idea pops into my head. Like a story about a one-trick-pony that falls for a dog-of-many-tricks?! Or not.