In my soon to start new d20 Modern campaign, the heros are low level (4), but are meant to be experienced, heroic individuals. My thing is, I like low levels. In order to give them a wider range of choice--as they could only get 1 level of most advanced classes--I created meta-basic, sub-advanced classes (shall we call them MBSACs?) based on the Fighter, Rogue and a PC version of the Expert. I called them the Combat Hero, the Covert Hero and the Capable Hero. The MBSACs are accessible at 2nd level. I haven't play-tested them, but the crew are liking them so far. I intended to release them free through Sword's Edge Publishing in the near future.
So, basically, yes, I think it makes sense.