I've yet to find a 1/4 foot that sewed an accurate finished seam (after ironing - tested by the 3 strip method).
If I have a project that demands a perfect 1/4" finished seam then I use the 3 strip method and move my needle position over. For example - if I'm sewing a pieced border and it needs to measure exactly 40" in length to meet properly at the corner.
If the project doesn't demand a perfect 1/4" finished seam then I don't worry about the exact size of the seam - but I do make sure that all my seams are uniform otherwise the blocks won't match.
BTW - I am also using a Janome and my usual piecing foot is the 1/4" accufed foot - but I've tried some of their other 1/4" feet as well.