I don't like removing buildings from the "production chain", because in order to lean how to play good you need to learn the basics first, if you introduce something that's too different from "original", you'll only get confused when you switch to "real" mode. For the same reason adjusting the building "ratio" might be a bad idea. One notable exception - I would actually remove towers from such game mode, this would actually encourage making an army instead of spending 20mins to make towers and this will actually reduce game time in general (and probably pt ?).
I was thinking about speeding up the game by adjusting the maps, increasing the starting raw resources might work but it's not ideal, players might just screw the economy completely and just make units (and we want them to have eco) so if we choose to do that then perhaps limit it so some small adjustments (+20 wood/stone, +10 food, +10 gold ?). It's not really to speed the things up but to give larger margin for error.
Making some actual new maps, where resources are easier to get (i.e. closer) and with some better positions to defend (if we remove towers), so a small amount of large "chokes" (more than one-two might be to hard to defend, too small choke will encourage camping while too big might make some strategies too effective, i.e. militia rush).
Other than that.. perhaps reduce amount of resources required to build (-1 wood/stone ?, of course this way we shouldn't give more resources at start, maybe even reduce it), while this changes the gameplay (paragraph one..) I think it's not that bad. Perhaps speed up building process itself (10 per tick instead of 5 ?, same for roads, fields). Speeding up the production process might also work but I don't think it's possible to do, afaik right now it work like this - "worker" is doing something, then rest for a while and cycle repeats, we shouldn't speed up first part (paragraph one again..), we might cut some time from second phase across the board but do we have enough margin for that ? (we can't change it individually because this would change the ratios).
*edit*
Few things like number of "ticks" required to build and maybe reducing the "rest" time should be pretty easy to do, so we might even test it fairly easy to see how it works in practise.
I'm only little concerned about this idea in general, the new mode might actually end up too popular and some whiners from TS might as well start complaining soon enough requesting its removal
*edit 2*
On a seconds thought, if we decide to speed up building process it should affect only building construction, messing with roads/fields could affect the balance too much (number of serfs/labourers).