Hi
This really depends on the function of your webserver app.
How many users will be accessing the same tps table at the same time?
Is this a heads down data entry system or just a reporting system?
A webapp with multiple users will perform much better than a regular win32 app since you are not sharing an exe or using a LAN. The question is how many people will be inserting or deleting records in a tps file at the same time. If you are using separate tps files for different companies this shouldn't be a problem. However, if you have lots of people inserting/deleting in the same tps file, you will start to see slow response. You can have millions of records in a tps file and if you have proper keys you won't have any issues, even with reports.
One other main advantage is that will rarely see corrupted tps tables.
I would say go the tps route and if you see any speed issues, try to solve it by using better indexing. If you see issues converting to SQL using FM3 is not that hard.
I am sure other people here and Bruce might have different opinion on this. That's my experience.
Regards
Bijan