Is a grease drip pan needed in a reverse flow

I built a similar size reverse flow.  I did not do a drain because I figured I would add it later if I really wanted it.  I have never felt the need for it.  If I were building a commercial unit, I definitely would but for a small backyard smoker, I don't think it is necessary.  I just put two 8x11" cake pans under the food and let the food drip into that.  I clean them about once a year.  I do think from my readings though that most people put in a drain.  but on your small unit, it will take dozens of dozens of cooks to even have the need to drain it.  You'll only be cooking one or two chunks of meat at a time with that size, not 10 at a time which to me, would warrant the drain.

my build in case you are interested.

http://www.smokingmeatforums.com/t/181548/my-first-build-help-me-please-reverse-flow