FWIW, I use (and wrote, so I'm partial) the public-domain-licensed OpenNETCF.IoC framework specifically for smart device use. It follows the CAB/SCSF object model, generally speaking, so if you're familiar with SmartParts, Workspaces, etc then it should be no stretch to move into it.
As for your laundry list:
- Different language support: No framework really provides this, but neither do they prevent or hinder it. We have a loose framework we use internally, but it's not really something that can be packaged and shared as it's more a methodology.
- Different Resolutions: Again, no frameworks that I'm aware of do this. There are different styles for handling this too. I prefer separate UI Views for each resolution, especially for portrait v. landscape. Docking and anchoring can only get you so far, but they might get you from, say, 320x240 to 640x480.
- editable grids: Again, not really a framework issue, but a control one. There are a few commercial grids that you can look at (like Resco)
- local database: We almost always use SQLCE. The query parser tends to be slow, but when you need speed that's what TableDirect and indexes are for
- needs to be fast: Define "fast". These devices are inherently slow. The IoC framework does a lot of work for you by caching things. It's as fast as I could make it considering all it does (and I'm always thinking about perf).
- best back-end: when was an ASMX service decreed the "best" backend? There is no right answer here. If an ASMX worked well before for you, then it probably will again. WCF is great for some things. Azure is great for others. It really depends on your requirements and topology.
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