First thing that comes into your mind is why you need this.
Seriously, if you're already using the system for quite a while, why to activate new features you're not sure if they migh suit you or not.
That's the question.
Parallel accounting, that's fine. If you were using FI-SL for this, that's fine, you were using parallel accounts- that's also OK.
From my experience, there's one thing I can memorize, when I was so very in need of parallel accounts, and it is one thing only- tax depreciation of fixed assets. From that point, running actual depreciation for assets for depreciation area different from 01, on real G/L accounts to me ,back then, sounded so very cool :)) Or revaluation of fixed assets.
I've tried to dig deeply into the issue. Not that much I know so far about the migration itself, but this is, at least, something.
First of all check for SAP note 812919 on migration issue. It gives you some hints, also provides you with quite useful links on SAP sources.
There's that migration tool, Migration cockpit which is used to transfer the data from classic Accounting to New
General Ledger Accounting
and, where necessary, to implement the new functions (such as document
splitting) in General
Ledger Accounting. This Migration cockpit tool includes some initial standard templates, so if you want to be aware of the consequence of steps you're going to deal with, while implementing your desired scenario (there are 7 scenarios so far, by the way), then you might take a look what cockpit's offering.
Migration to the New G/L has to be considered as a separate project, which is ,on average, 6-8 months length. Why for so long I am wondering, and what is the scaling of 6 months migration project (how many company codes, what functionalities involved, what features are being activated and things like that).
3 phases of the project, 8 possible scenarios, 8 months length implementation... what else should be mentioned. 2 training courses available, one is for New G/L itself and another one for migration. I guess, latter is pretty new one..
It says that just a regular consultant is not capable of implementing migration, so there's that special migration service team in SAP you have to deal with while doing this thing.
Scenarios...
From 1-8, they are ranged by the complexity, i.e. features included in each scenario. Say for instance, only parallel accounting, no document splitting... or parallel accounting + document splitting... or everything mentioned before, and Controlling stuff and etc. Scenarios 6-8 for customers already working with new G/L, they have just decided to add some more feautures in it.
It is way too risky... So even if you're doing it yourself, with no SAP migration people involved, think twice. I personally, if there's that super urgent need in using new G/L, I would just do the copy of my current system, with new G/L stuff activated in it, and would start from there, without ruining anything.