I'm a loyal and happy customer of DH and have no plans to move. I have noticed however that people including myself have been asking for Mono support for about 6 years, and the DH line is "when there is enough demand we'll support it". But it's still not here. C'mon guys, with all of the things that are chosen to be added to the environment, this IS an often-requested feature but it's never implemented.
I'm of the opinion that there is some sort of techno-religion going on at DH where some misguided people think Mono=Microsoft so they're not going to consider support. Mono is not a Microsoft product. It's completely FOSS and at this point it's very mature.
DH, you have developers like myself paying other companies money to host services when many of us would much rather be hosting everything here, even if we need to pay for VPS.
My recommendation is for DH to look at the wiki docs and related blog notes that have been written about supporting Mono on DH/VPS. See if these will help with implementation of Mono on shared servers. If not, please consider offering Mono as a built-in and supported stack on default VPS installations. I would probably go for that!
From a marketing perspective, DH could draw a LOT of new business by advertising support in the Mono community. Right now that community is fragmented on where to host their software. Contact Miguel de Icaza or other Mono leadership and propose some collaboration. I'm sure they would work with you to allow Mono to become a supported option for all DH users.
The only other way I can think of to get this initiative moving is to get a VPS myself, go through the process of installing and configuring Mono, working closely with DH Support to ensure it's completely functional, and then reselling environments like this to the Mono community. Honestly I'd rather be a user/developer than a value-add reseller in this regard - but I mention this because someone else might want to do this.
I'm hoping that other .NET / ASP.NET / Mono developers will add their "me too" to this thread, but that should Not be the metric DH uses to decide whether or not to support Mono. Supply must frequently precede demand. "Build it and they will come" sucks as a business model but sometimes that's the only way it can work.
Thanks for your time and consideration.