Regarding VIP vs Premium value discussions i think that allowing VIP's to have a VIP-only benifit is a good choise.

TR and start at lv4. I would love that.

If you want a shop option : allow a 'upgrade' option to all customers:
Premium & VIP start 3 levels higher resulting in Premium with option start at lv4 (as standard VIP) and VIP with option start at lv 7.

Leveling at low levels is so fast that it's not that big advantage compared to free/premium.

/curbo