Just wanted to share (and collect stories) about switching to an adjustable. I switched form a Parker R22 to a Gillette slim (thanks Jake!).
A whole different experience. Here's why:
1. With the Parker, I had to wait a couple of days between shaves. Otherwise Dexter (my parker) would take its toll on my skin. With the adjustable, I can set the aggressiveness really low for frequent shaves.
2. I can change the settings to match my technique in certain tricky areas like the neck, mustache and chin.
Although I believe you can be happy without an adjustable, I think it may be interesting to try one and give your reasons for, against or neutral about them.