SPL-Experiences needed

Hello Informix-Users, we are planning to convert a big, mission-critical application written entirely in C and 4gl in a Server-sided SPL-functionality. Therefore, I'm looking for someone who has made some experiences in the use of SPL. In detail we are planning to use about 30 Stored Procedures in one Online-Instance. Each of them consists of about 300 lines of code with max. 3 SQL-Statements (Insert, Update or delete). The max. amount of nested calls is 3, which means that for one transaction up to 3 Procedures are called. We are running Informix.Online 7.22 on a AIX (4.1.5) RS/6000 (J40) with 2 Processors, 1 GB Memory and 16 GB SSA-Disks. The server is accessed by appr. 80 Users in peak times. So my questions are : Are there any experiences out there in the use of SPL in a case similar to ours ? I've heard about a memory leak problem with SPL and Informix-Online 7.21. Is this problem fixed in 7.22 ? How about performance ? Is a ESQL-C design better ? If you have any comments to the questions above feel free to give me an answer (e-mail preferred). Bye J'rg