Is this a recommended way to go for the moment?

A question about gear combination.

I currently own a 40D, the canon 17-55 2.8 IS, the canon 55-250 IS (both are for crop censor cameras only), and the $100 Canon 50mm 1.8.

I would like to go full frame (5D original). But to do so I would have to make a huge investment since I won't be able to use two of my main lenses.

But the 35mm 1.4 L has caught my attention. It is $1,360. But from what I hear, worth every penny.

So I'm considering maybe purchasing this lens for the moment and taking a good step forward in improving the quality of my images, and to help me build a better portfolio.

In a year or so I would have enough to maybe purchase a newer version 5D and the 70-200 L.

THE BIG QUESTION IS:
Now would it make since, for me, working to be a better wedding/event/model, photographer, to then continue to use the 40D along with the 17-55 for events in changing environments, and also interchanging with the 5d and the 35L lens, and why not the 50 1.8 lens, to produce the better shots. And of course the 70-200 on either camera depending on how far I'd like to reach.

More than anything I'm curious if this would be practical. I love prime lenses, and I really don't mind walking back or forward to get the better shot. But I don't want to drop so much money if it worn't be too practical to begin with.

Any advice is really appreciated. Thank you, Luis

This might have been better suited to the Lens or Camera body discussion section of the forum - you would have gotten a quicker response there, methinks.

As someone who has shot with a 40D and a 5D (and still do), I find it advantageous to be able to switch to full frame to crop and here's why:

My 40D gives me slightly longer reach, which is nice when I'm basically banished to the back end rows or sides of churches while still maintaining constant aperture, using my 70-200 lens.

My 5D has the 24-70 on it, and it's my main bread and butter setup with the Quantum flash I have.

In your case, I'd probably sell your 17-55 2.8, and purchase a 24-70 2.8, a 5D, and a 70-200 2.8 - Sigma and Tamron make pretty good ones.

Yeah you're right.

Though I also wanted the opinion of those who shoot for profit, in demanding environments, scince I'm wondering about practicality. So that kind of fits here no?

Honestly I could get the money together to do just that. It just seems like so much !! haha. Reason why I was considering the 35mm L for the moment to see if my business improves first then make the bigger investment.

Thank you for your advice!

OH, I've had bad luck with sigma. And don't really like the look to the photo that Tamron's produce. Just a personal preference I guess.