My name is spelled Jen. Not Jenn. The extra N annoys us Jens that have chosen a life of a single N'ed nickname. That extra N looks like we're asking you to stutter when you pronounce it. One N is enough.
HOWEVER, my full name is spelled Jennifer, and I think Jenifer looks positively freakish and misspelled. I am ok with this inconsistent rationale, but for reasons I can't really justify except for that's just the way I like it.
Jenn...me no likey
Thanks for your attention.
NOTE:***I uphold the utmost respect for all the Jenns out there. I don't begrudge you for wanting your extra N, it's what's normal to you. I just don't understand how you're able to get up every day and face the world. That's all.