Here are the specs for a pair of Tower & bookshelf Polks.
R50 Tower speakers
Overall Frequency Response
40Hz - 24kHz
Lower -3dB Limit 50Hz
Upper -3dB Limit 20kHz
R15 Bookshelf Speakers
Overall Frequency Response
60Hz - 24kHz
Lower -3dB Limit 65Hz
Upper -3dB Limit 20kHz
Bookshelves usually can't be pushed as hard as towers since they will run out of steam sooner
Setting the speakers to small helps to take the stress off the receiver & lets a sub kick in sooner to do the heavy work rather than trying to push your mains to do it. (depending on where you set the crossover at.
Like I said, people do use bookshelves for thier mains. go for it.
But would i not need the full range of a tower if i have a sub. With a sub in place wouldnt I run the towers as small speakers on the receiver setup? maybe i would still get really good mids and highs.
When you say they have their limitations, were you refering to the bookshelves or the towers?