Ancelus is the safe choice if your goal is to minimize disruption to an existing application. In many legacy systems there are only a few functions that are trouble spots. In these use-cases Ancelus is often integrated to solve only the specific problem.
Ancelus Integration into SQL (or PHP, etc.) applications is straightforward. You simply use Threaded Query Language to get results back into the legacy world.
TQL queries are created in a point-and-click GUI (TQL Prepare) and stored as XML. The stored query can be directly inserted into the application code base (TQL Execute) to launch high performance Ancelus queries and return the results to the existing application. The rest of your code remains untouched, including the post-processing often done in SQL, PHP or other tools.
The development of the Ancelus schema for the add-on module is also straightforward. The Entity Relation Diagram is the Ancelus schema. No transforms, no tuning, no surprises. Draw the ERD, type it in, turn it on.