Hello Miller,
it mostly depends on what type of external objects are used in your application, and what kind of operations (logging? user-friendly message handling?) you need to trap via TRY ... CATCH.
PowerServer toolkit will automatically comment out your NVOs because PowerServer offers its own built-in exception handling mechanism to avoid client side exception.
This is typically just fine for most of the cases.
However, if you need to call external DLLs or COM objects on the client machine you may argue that the lack of support for Exception is not gonna let you handling properly runtime errors.
In short, you have no means for reusing whatever custom function or event is implemented into your NVOs.
This is not gonna affect migration of your application, no matter how big it is and how loaded it is of Exception-derived NVOs.
But it does affect its execution if exceptions thrown by external components are meant to change the application execution flow.
Best,
.m
Your code will keep working in client server, but will be automatically skipped when deployed as a Web application.
One source for both environments, with no need to comment/uncomment lines out.
As a matter of fact, just to alleviate your concerns on Exceptions handling, keep in mind that - unlike a PB executable - the Web application will not "crash" when exceptions occur.
Of course you'll receive "user-unfriendly" messages, but the Web app will keep running.
Best,
.m