A narrow blade isn't detrimental as far as I'm concerned- at least not unless the trigger pull weight is excessive. Then, the extra width can make it feel like the pull is lighter than it actually is. But otherwise it's more or less of a wash to me. Most any trigger I use will get smoothed on the right edge if too sharp. Purely a preference thing. An example of one that doesn't feel good to me is the Spa CP-1M. And the guard is so small that a shoe would make it way too cramped.
Quick question for Steve and Mike: Are there any plans to produce anything for the Spa CP-1M? Myself, I would buy a decent grip in a second! Same for other 'enhancements' like a good trigger guard, triggers, sears, hammer debouncers- any of the usual things people use on CO2 pistols.