from what i know, all zim isp's now peer at zinx.. including powertel and telone/comone as of end of last year... so local hosting is still quite relevant i would think..with regards to website access speed. the way i see it.. the faster the site responds.. the more hits you get...and people enjoy using your website much more. that being said.. ISP's and your internet connection can change that experience for the end user..but from the website side of things.. you should do as much as possible to optimise your site for speed.
the thing is.. generally speaking.. browser caching mostly addresses end users with speed for site access.. and most people in zim are okay with waiting 30 seconds for a page to load.. so things like cloudflare and other specialised caching servers only really become relevant when the site is getting huge traffic... and the current hardware cant scale with that demand. i.e your site runs fast when theres not many hits.. but when the hits come.. then its very slow and unresponsive. its a complicated thing..but really just depends on your requirements for your website.