Originally Posted by
BCDrums
I am using an old Shimano Deore XT M730 front derailer. Has been on the bike since 1990. I won't be changing that out, because it has shifted reliably for 29 years. But I agree with you that the current higher-end front derailers limit the shifting possibilities. I tried a modern one last year, and it wouldn't shift at all, because I didn't have exactly 10 teeth between rings.
The XT probably won’t play well with an STI shifter. The pull ratios are different. You may be able to get it to work but it probably won’t work very well. For 9 speed and below, a rear derailer will work with either road or mountain shifters. The same can’t be said for front derailers.