What do you like more, fresh lemons or mangos? Can you get quality fruit at a fair price at your local farmer's market or grocer? How much of a slave to your plants are you willing to be? These are questions I'd ponder.
It's kinda like veggie gardening. I only grow what I know will get me quality produce with limited inputs that is either too expensive in the store or of poor quality. Tomatoes comes to mind and speaking of maters, I'm a variety research freak. We have a new tomato that you need to get your hands on - BHN 602 aka "Rodeo". Out of 4,500 tomatos trial, it was selected #1 at the 2012 San Antonio Stock and Rodeo. Think of the richest, sweetest, reddest 10 oz tomato with a skin that is very resistant to cracking and catfacing but melts in your mouth, produces like crazy and that's BHN 602. Much better quality than the current trend/fad back to heirloom tomatoes, which I think are of poor quality and taste. Asparagus is another one that's worth planting. Out of 9 crowns planted 2 years ago, I've picked so much asparagus we're sick of it! I'm letting it go to ferns.
Regarding the lemon's root system - head down hiney up! Sometimes I spray an unwanted tree like that with glyphosate to kill it and allow the roots to rot a bit, then yank it out. Otherwise, you're gonna have to sever those roots and then dig it out by hand. I cheat and use a chain and my tractor's bucket to yank stuff out too, but I doubt if you have that luxury.
Mark