FWIW, I always play with Spur. And I don't care about times in Hell, I guess my best time ever there is something over 10 minutes.
I like Spur mostly because it doesn't need leveling up. I personally hate the Nemesis, because I can't ever seem to avoid the levelups scattering around.
My advice for getting through hell & ballos is this:
1) Make sure you have the life pot when you enter the hell. Yes, this means you can't use it against the Misery-Doctor-Undead Core boss run. Deal with it. If you can't do that, you just need to dodge better (also, see point 2).
2) Prioritize "not getting hit by enemies" over "speed" or "upgrades". Try to find safe spots, and keep your head cool. Learn to watch where the butes are shooting at. Whenever you can safely snipe your enemies instead of risking it (even if it means it takes more time), choose safe sniping over risks. (I guess this is more relevant to Spur, with it's sniper characteristics and slow load-up. You should learn to always keep it recharging whenever possible, even if you're jumping/boosting.
3) There are points in hell where you need to be quick to survive: the corridor with falling blocks and heavy press fight. Unless you're really good with dodging, do not try to recharge your life with killing those endless butes in heavy press. And the falling block corridor is just evil.
4) finally, Ballos: Learn the patterns and keep your head cool. Prioritize your safety over piling the damage on him, i.e. Don't take useless risks with attacks. There will always be another opening to shoot at. Learn to see when you're late to that and that opening and retreat for the next one. That's all there is to it.
...although I have to admit that the last form of Ballos still makes me go gaga and lose my cool. Usually that equals me getting killed... but I lack the skill to fight it any better than that anyways, so...