iCalamus runs smoothly on my iMac dual core. the only thing i miss is a decent documentation. a piece of software that costs over USD 100,- should include a decent manual (preferably in a printable version - or as a buying option). OTOH, iCalamus is rather easy to handle if you have some experience with DTP (x-press switchers will find iCalamus a relief!).
some functions are still missing (no PS export; or i haven't figured out yet how to streamline certain tasks: e.g. giving all pages a new background colour in a long document with just a few mouse clicks... these issues are probably due to the rather short history of this piece of software and will be resolved soon... i hope).
the price is a bit steep currently (considering other options), but again: if iCalamus continues this way ver. 2.9 should be a real bargain at this price! its an investment in something that looks good. multiAd Creator light is only 99,-. and can do a lot more than iCalamus - yet it is only really valuable for single page docs... ragtime has stopped its "private" version and is thus unaffordable for the rest of us, so iCalamus has a lot of opportunities.