• glue code
• converting C to assembly with Keil

i think that by the time you have gotten into coding with assembly, and can think almost as fast as you type :), the difference will not be that much.
C:

• faster processors


• more RAM


• upgrade path available


• more developers available

assembly:

• slower processors


• less RAM / fixed RAM


• limited or no H/W upgrades available


• likelihood of hitting the RAM/performance boundaries at some point


• S/W developers' time vs. H/W developers' time (re upgrading)


• development time available to convert C to assembly, or to code in assembly rather than C


• personnel available to code and review assembly (less likely than with C)

re the last point, you may have trouble finding code reviewers who can review 8051 assembly (this is somewhat of an understatement).

and re the C list, it is somewhat overstated. coding applications in C is OK on lower-performance systems, but if you hit a wall with RAM or performance you will need to upgrade or probably convert to assembly for optimization. the project i was working on used a radiation-hardened 8052 for space environments, no onboard or offboard RAM except for the 256 bytes of chip RAM, no upgrade processor available, no hardware design changes available to help the code. so i was stuck, and probably most projects would not get stuck in that way.

anyway, i think coding in assembler is more fun than C. you are right there down with the processor.

james