I found Savlon fine, but Bepanthen better. I didn't lose any colour from Savlon on the whole, but I lost a few more 'chunks' from scabs falling off. Bepanthen kept it more supple for longer.
All you're really trying to do is keep the scabs attached to you for longer, when it comes down to it. I've found Bepanthen best. Savlon's fine, but Bepanthen is better. You need to reapply it less often, that's the main thing. Keep it moist, keep the scabs on.
When it all comes down to it, if you lose the odd chunk you can just get it touched up, but the less touchups required the better, and the general condition of the tattoo is important. Look around you when the sun's out, you'll see a lot of tattoos with great chunks missing out of them and awful patchy blacks. As long as you do
something to look after it while it's healing, you'll see less of it, and in my experience (partly my own and partly handed down from my favoured tattooist and my other tattooed friends/acquaintances), Bepanthen is best