There are a couple of issues with going FvS instead of cleric:
- Your spell progression is one level lower, which means if you take more than two non-FvS levels, you lose lvl 9 spells. Given how feat-constrained this build is, losing a feat is a tough call; but so is not having Mass Heal on a healer.
- On the monk version, having high WIS benefits both your AC and ranged to-hit (Zen Archery); if you go for a FvS who dump-stats WIS, you lose out on both. You'll also hurt your DCs, limiting your versatility; my build should have reasonably high DCs.
- Obviously, you lose Radiant Servant, which is a pretty nice feature for a healer.
On the upside, FvS get a lot more SPs, of course, and if you go Silver Flame you boost your longbow dmg. So there are definite tradeoffs.
I haven't really thought about combining artificer & cleric, but what you're describing is quite different from my build, not least because AA & crossbows don't mix. I also haven't figured out if rune arms do enough to be worth an arty splash instead of, say, monk.