Islander, i've run yammy's on all my boats but i think the big block V6 yams are thirsty and this is the compromise for reliability (in my experience anyway). Came from a 4.2 225 yam on a 6.5 riptide platey. Averaged about 0.8km per L. Just went to twin 140 zukes on my new 6.8 riptide (both cab boats) and i'm getting around 1.1km per L combined on a bigger, heavier rig. I recon the new mercs are a great spec, twin 115 merc were my first preference over the zukes but i had other dash and gauge challenges (already fabbed) to overcome. This said 200 hours in and no complaints from me. I agree with others that all modern 4 bangers are pretty sound things, its also a matter of finding the best spec for your boat. Weight, torque curve, twin/single etc. My mates new style 2050 stabi handles weight aft way better than my old mans original shape podded 609 does. 2250 with twin 135 mercs, now we're talking!!! Nothing more fun than getting into a new rig, great boats the Stabi. My old mans is around 15 year old and still going strong, few bumps and scrapes but no cracks. good luck.
Scott