I am for having possibility to select compiler in "new from template". It might be good to draw all teplates for any compiller in "new from template", but to draw templates unsupported for that current compiler grayed out (disabled) maybe even with small icon overaly (like shortcut or network share has) to notify user that they exist but are not supported for that compiler, because of some technical limitation.
Nothing is more annoying like message box popping out "after the fact", it should be avoided as much as possible, user should be aware in advance what works and what doesn't. Thats my idea.