Flavor depends on wattage first, then other factors - filler, plastic, metal off tastes. Older versions of RY4 could handle various wattages pretty well but that was when there were only a few choices of ohms/attys. Personally, I can 'taste' filler, so I stick with the eGo-c system, but lately moving to the non-filler CE4,5, vision stardust and the CC Carto and Tabac BCC carto. Taste is better for me in all of those compared to any cartridge or carto with filler. The eGo-c can be light on throat hit unless you're using an LR and a strong flavor - tobacco, coffee, menthol. The others mentioned do better with throat hit as well as taste and vapor. You can get the CE4's and 5's (changeable coil) at many vendors and the CC Carto and Tabac (both changeable coils) at heaven gifts and good prophets. The Tabac is the most recent version and solves some of the problems with the CC and the stardust, imo. I'd suggest getting the changeable coil types - that way you can vary the wattage - they all fit well on the eGo although you'd have to get a non-eGo connection or an eGo adapter for use on the SB.
My guess is that the 1.5ohms is likely too hot for whatever RY4 you are using presently. You could try the popular Boge 2.0 carto but if you're still getting 'the taste', it's likely that you like me and others have a sensitivity to the filler. Some people don't taste it - I'm happy for them ;- )
