i agree with using steeping grains in extract. the only time extracts should be giving you weird flavors is if you boiled the entire amount for the entire 60 minutes (which will also give you a darker finished product) or you're dealing with old ingredients.
from my research, LME is more prone to becoming stale than DME, so if your LHBS isn't a big one that's always selling out of their products, maybe stick with DME.
if you go with just an all light DME with some specialty steeping grains, you should be getting just about the same product. i also only do 25-30% of the extract for the full 60, then i add all the rest at flameout actually (your product should be "nasties"-free, but even if you add it at the end when the temps are still above 200, you're killing anything anyways). this helps if you're going to do a hopstand because the time it takes and the stirring in of the extract brings down the temps to the perfect level for the hopstand.
sometimes when converting a recipe from all grain to extract, people also talk about that you get a bit of a sweeter final product (extracts tend to have less fermentables depending on where you usually mash at), and one way i've found to avoid any residual sweetness is just to add some sugar to help dry it out.
the steeping grains may seem like they add more time, and although i'm going to recommend this, i've never actually done it: they say to just stick your grains in when you start the boiler, take them out once you reach the 170F mark, then you're utilizing your warm up times to do both. it may not be exactly extracting all the sugars possible from the steeping, but it will give you the flavor that you're looking to get out of it, since the main purpose for you is just extracting the flavors. also i've heard double crushing the grain is best for steeping, and i've done it with some success, although that's just anecdotal success.
in other words, i say go for it!