Our main product has been developed in time through various languages, Retrieve4GL (Sage Line 100 DOS language), Clipper 86/87, 5 and 5.2.
We also had a parallel (albeit far behind in feature set) product written in 4th Dimension (a database/IDE/runtime client/server all-in-one product) for use on Mac's.
As Clipper was coming to the end of it's shelf life, we started dabbling in Visual Objects and also Visual Foxpro, to see if they were worthwhile development platforms to take the product forward.
We wanted a cross-platform product, hence dabbling in Visual Foxpro 3... luckily we didn't go that route, as VFP3 was the last version for both platforms.
As Visual Objects was also proving to be a non-starter, we pulled out the old 4th Dimension Mac product, and with 4th Dimension becoming a cross-platform product, we quickly ramped up the feature set of the 4th Dimension product and created an export from our Clipper product and import for the 4th Dimension version.
4th Dimension, evolved it's name into http://www.4D.com , and as it's products matured, they added more features, (all built into the same single product/exe file)... odbc, web server, sql server, php server.
The language has evolved to allow native SQL statements, in addition to it's traditional query/'venn diagram style' sets.
Now, it's not perfect, (as if anything could be!), and we are now pretty much tied into it, but it has served our purposes well.
The ability to just copy a single folder on your PC/Mac, and suddenly you have a working database/web server/sql server/IDE, is many degrees of complexity different, to say SQL Server+IIS+IDE. It makes it also relatively simple for our customers, who know they have one server App, which takes minimal configuration for it's setup, and then for the client, either a browser to open, or the client software to simply copy in and run.
I post, only becuase you appear to have had a similar early development path as our product.