Others have said that they don’t mind front loads in bar bags on their Rams; Andy did notice it; I too noticed it. I daresay it comes down to what a particular rider “noticing threshold” — at what point a handling quality becomes first, noticeable, and then, annoying. And I would also guess that it might have something to do with your riding position. I set up my bikes with a rearward saddle position and knee well behind pedal spindle, which would leave the front end light except that I use drops and so put more weight on the front wheel than with a swept back bar. OTOH, when I’m climbing seated, I’m shoved back with hands lightly resting on the ramps.
I haven’t noticed a tendency to wander when climbing slowly thus seated, at least on my various custom roads and on the Ram, at least, if there is a tendency, it was negligible; where I did notice it was on the first edition Sam, where yes, indeed, it was annoying. All bikes unladen in front and with and without rear loads. But I daresay that adding 10 lb to the front of these road bikes would indeed exacerbate the tendency to the point of annoyance.
I did noticed even very modest loads on the front of my ’99 Joe Starck gofast, though this was with one of those very old-fashioned bar bags that uses a steel bracket that slips over the bar and under the stem, with prongs that fit into sleeves on the side of the bag; thus holding the bag an inch or two out from the bar. But I had only 3-5 lb in the bag and it was very noticeable, tho’ not to the point of intolerable, just annoying.
At any rate, for my Rivendell road bikes and others modeled on them, I much prefer rear loads. I did ride 2 low-trail bikes with front loads and didn’t care for their handling. The first was a Kogswell Porteur (I think that was the model; at any rate, it was low trail and had a big platform rack on front to which I attached some medium laden panniers, perhaps 30 lb total. Unexceptionable handling, but I much prefer the handling of my Rivs and didn’t take a shine to it.
The second low trail bike I owned and rode for 18 or 24 months: an otherwise lovely 1958 Rene Herse (the old builder, not the modern company) with custom front and rear racks. That bike fit perfectly from the first ride and was one of those rare gems that consistently in all conditions encourage you to ride 1 tooth smaller in back, but here too I just didn’t care for the handling. And it didn’t take well the sometimes heavy grocery loads I carry, either in front or in the rear. Even unladen I found the handling, what, dull or unexciting, the opposite of that signature Grantian handling of supreme straight light stability with unerring turn-in in corners. So I sold it on.
Different strokes for different folks, as the refrain went from that archly annoying song by Sly and the Family Stone. But man! I do love me the handling of my mid-trail (I guess) Rivendell road bikes, unladen or with rear loads! — that Sam notwithstanding.