Should i move to filing under presumptive tax 44da?

Dear Friends,

I provide software services - freelance/seft-employed. If my income is 40 lakhs and my actual business expenses are just 2 to 3 lakhs, can i still file taxes under 44DA and pay (40 * 0.5) x 0.30 = 6 lakhs income tax (approximately). Is this perfectly legal? I don't want to do this if it is a grey area.

As of now, I have a private limited company and give out almost 80% of the company's income as salary to myself. I end up paying 30 to 33% tax on my salary. If the above is true and again 100% legitimate, I want to get income in my personal name and move to 44DA starting FY2018-19. 

Thanks.