I don't mind job hoppers, as long as it there is a mix of longer terms. Job 1 - 3 yrs, Job 2: 2 years, Job 3: 5 years, Job 4: 4 years, etc. In this day and age, the best way to climb the ladder is to switch jobs. It's rare to get a big salary increase if you stay in the same company (even with promotions). Many people (incl DH and I) got 30%+ raises by moving to another company. We both continue to have good relationships with our previous employers (don't burn bridges), but everyone understands career moves.
I was also the sole employee in my last job. It was hard to leave because they did depend on me. I compromised, stayed to finish my last major project, and did volunteer my time to train my next 2 replacements. They are on replacement 3 or 4 now and I'm not hugely impressed with the current one and have heard multiple complaints. She's been there about 2 years now though, so she might stick.
At my office, we even hired someone who stayed just about 2 months. He then finally got the job offer he had been hoping for (he had interviewed with them and with us), and he took their offer. We understood and he left on good terms. We couldn't match their generous offer and had absolutely no hard feelings about his choosing the best opportunity for him. We told him congratulations - we wish you the best (and meant it)! I was rather bummed though - he reported to me and I still miss his skills.
But only move if you get a decent offer. no harm in looking, but you are in the fortunate position of not having to take something that doesn't improve your life. I'm happy in my current place. But a year ago, I saw an opportunity for a really good position with MUCH higher pay. So I interviewed. In the interview, I was flat-out told that they didn't believe in work-life balance. I withdrew my application, telling them honestly that while I liked the job, I needed more work-life balance.
