I am going to answer based on my experience. And hopefully an advisor will come and give you better advice.
So basically when you cancel you asylum, you basically closing that chapter, you lose any benefits and protection that asylum seekers get. Your stay in germany will be dependant on the ausbildung. If you decide you dont want to do that ausbildung anymore, you will be at high risk of deportation if you dont find an alternative or if the Ausländerbehörde refuse to give you a residence permit for your alternative.
Since you said your lawyer advised you to go for AufthG 16g, if he is a good lawyer, he has looked at the asylum case and possibly also looked at the success of you getting this Aufenthaltstitel.
Everything has pros and cons. Weigh them too for yourself and then make the final decision. Also contact your Ausländerbehörde and ask them if they will give it to you.
So for me, i am an asylum seeker too, i recently cancelled my asylum advised by my lawyer because my asylum case is very week and also i have advisors from asylum centers guiding me in this process.I contacted the Ausländerbehörde before canceling and they asured my success in getting 16g once my asylum is completed. I know someone who cancelled the asylum in March and got this 16g in June/July.
There is not much information from people who went through this process for us to have more testimonials, but we work with what we have for now.