Hi - I'm new to the forum and have started biking for the summer. I'm riding a ~1991 GT Talera that I bought new many years ago. I'm enjoying the riding and plan to continue indefinitely and am considering upgrading to a new Hybrid.

Based on the miles I've put on this summer, I'm pretty certain I want slicker tires, front suspension, and more comfortable handlebars (flat bar, but need more sweep). Rather than invest in those on my current bike, I may just get a new bike. My question for you folks is, am I going to see a noticeable difference in shifting, drive, or anything else relevant between the families (Shimano in this case) of derailleurs?

I ride only on the road - no trails. My bike has Shimano Exage 300LX components and they shift pretty cleanly. From what I've researched on line, they seem to be equivalent to Alivio. I do plan on riding at the bike shop, but I don't expect a short ride in a flat parking lot to tell me the whole story on a Deore or SLX system. Are they worth the $ and will I notice any difference?

Thanks.
Rich