Just wanted to weigh in on the 'loud enough to hear myself' and 'loud enough to wear earplugs' discussion...
There are so many variables factoring into hearing yourself that it's pretty tough to compare with anyone else's experience -- size of your space, proximity to other amps (and how far you are from your own too!), drummer's volume, type of music, etc...getting one or more of your speakers up closer to ear level is huge, using walls either next to or behind your amp also. I was able to get through a practice with just my Rumble 40 a few weeks ago (it does have an upgraded Basslite S2010 speaker) but I did have to ask my drummer to play as softly as he could, elevate the amp to about 4 feet off the ground and stay pretty close to it. At higher volumes you might be missing the feel of your notes in addition to the sound, in that case more speaker area (either by more or bigger drivers) needs to be added in addition to power. For me the modular setup of head plus 2 1x12 cabinets, (formerly 2 2x10 cabs) is enough for playing with drums, 2 guitars. keys and vocals/a wind instrument etc...I've used a number of different heads rated from 300W to 800W, including a V2 Rumble 350 and a V3 Rumble 500, and they were all fine in terms of max usable volume. If I am 100% certain I'll only need one cab it's nice to be modular but even at lower volumes two sound better and I can hear myself without having to turn up as much. I had a chance to demo a Rumble 200 for a couple weeks, it kept up sorta OK with a full band but (imo) it doesn't give you that cushion that the 500 does.
And about ear protection -- it's true that you are doing damage to your hearing long-term even if you're not getting that "can't hear a damn thing" feeling, it's also true that prolonged exposure (meaning for example a 2-3 hour rehearsal) is a lot worse than momentary exposure. A drum kit for example is well over the 85db threshold for long-term damage at (usually) 100+db, so if you need to be heard over that you're doing damage for sure. I'm pushing 50 and used hearing protection more often than not -- I'm still functioning OK but have pretty profound and noticeable hearing loss. Don't mean to preach, but musician's earplugs all the time are really a good idea.