While I'm not sure how higher exposure on premium network is, compared to that on standard network, below are few important things to keep in mind, from my experience.
Premium network is good if you like things being fully automated. I.e. if buyer hits BIN button, the domain on premium network will be transferred automatically and the transaction will typically close in .ca 10 days. As no manual work (supposedly) is involved, the probability of delays is much less than that in case of standard network.
Premium network has some disadvantages compared to standard network. Domains on premium network will become inactive ("in review") as soon as they expire. In order to make them active again, one typically needs to remove and re-add them into account and ask the account rep. to "push them live", because such domains not always go active themselves once entered "in review" status. If one has many domains, it is a pain.
In case of standard network, expired domains don't get delisted automatically once they expire. It is good if one is going to renew some of expired domains because in this case there won't be hassles related to removing/readding/asking to make them live again. It has disadvantage, however. If domain on standard network drops and gets re-registered by someone else, it will still stay active in one's account. If then domain sells, one will face consequences of selling the domain which one doesn't own. The problem is the main Afternic sales channel is GoDaddy search route, so such consequences might arise quite often.
Furthermore, despite domains on standard network require manual work related to submitting the auth code/pushing the domain to Afternic account as well as the work performed by the Afternic rep to push/transfer the domain to the buyer, nowadays sales on standard network often close much faster than those on premium one, maybe because of manual oversight involved. Nevertheless, manual transactions (standard network) get delayed much more often than automatic ones (premium network), so often it is required to remind Afternic reps to proceed. If one needs predictable cashflow or doesn't have enough money reserves, then such delays sometimes can be troublesome, so in such cases premium network would be more suitable.
