it is if you can and have the tire choices. for those that need a tire to do double duty on the street and autox (and don't have to worry about poor weather) the old azenis sport seems to be the choice even though it's a compromise on rear tire size (the rear still has a bigger contact patch because it's being stretched onto a larger wheel). the new azenis sport will have a 225/50 15 supposedly so I would image that folks will start using that for the back.
Oh, and I'm in the same position as you. Looking for new tires for the stock 15" wheels. I autox for fun once or twice a month, but I want to keep the car very street friendly and not worry about weather and mileage too much. I'm working on a budget here too. I've narrowed it down to the ES100's or BF Goodrich g-Force Sports. 205/50 front, 225/50 rear. The BFG's are supposed to be super quiet and very nice, while the ES100's grip a little better but are noisey. The BFG's will last probably twice as long as the ES100's too.
I have 225/50/15 ES100s on the rear of my car ATM and to be honest I don't think I would get them again for the stock rims.
They are fine for "normal" or even lightly sprited driving but it doesn't take much to loose traction in the rear. Especially with a better tire upfront (S03's). Going straight all they will do is chirp but on a turn its nothing to get them spinning. I havn't noticed any real noise from them either but I also have a Blitz Nur with a downpipe so that is probably louder than the tires.
Overall, if you aren't going to drive it hard the ES100 is a good choice and are cheap. I hear they are a much better tire in larger diameter rims. I may try them again when I get new wheels.
If Falken makes these new Azenis in 225/50 I will be getting those for my 93' rims. They already have prices out for the 205/50 but there is some debate weither they are going to make the 225/50 or not anymore.
don't skimp. absolutely get a set of dedicated snow tires if you are planning on driving in a snowy mountainous area. steelies with snow tires (14 or 15") won't cost that much (probably $500-600) and will last you 2-3 seasons, depending on how much you drive. then have your stock 15's with summer tires for the rest of the year.