I don't see why Citirx would not be a grea advantage in this situation. If it's literally hundreds of users. the maintenence costs down the road to keep them all updated with the latest versions of the front end would pay for the server farm in no time. Large deployments are no more trouble than smll ones with Citrix, once you establish a baseline server config. You can add more to the farm as the application grows. To properly plan it, you need a reasonably accurate number on true simultaneous usage. You might have 500 total users, but if analysis shows there are never more than 100 on at a time, that's a big difference in server requirements. If it's a mission-critical app, I strongly suggest lots of smaller servers, rather than 2 or 3 monsters, because of the potential for downtime and loss of productivity.
I did a large install for a nearby company (I'm right there in your neck of the woods) which ended up with a Citrix farm of around 16 servers, to deploy the HR package they bought. The vendor INSISTED it would work fine over WAN connections, but they tested first and it was unusable, so they brought in Citrix and ended up using that for the distribution mechanism. The only downside in their system was that corporate politics resulted in it actually being 4 groups of 4 Citrix servers plus 2 SQL servers at each of 4 major facilities throughout the country, rather than having it all located in their Allentown data center. Then they had to add an extra layer with 2 more SQL Servers here that aggegated the data from the remote offices.