Ok, there are a couple of hills, but think of the descents!
Yes, if you are aiming for Stirling then your route via Crieff is more sensible.
I assume if you have an aversion to hills you are going via Aberfeldy and the A826? If you fancy a real hill, take the minor road from Kenmore over to Amulree via Glen Quaich!
I did the Glen Quaich Road (which is it's name, says Crieff Tourist Info) last Tuesday at the end of a 75 miles long bikeride before I pitched up my tent at the top of the mountain.
Glen Quaich Road is one of the hardest and best climbs I have done in Scotland. Absolute vertical from the bridge and up. No pictures or Google Earth can do it any justice. Thankfully, there were both some good fences and grass verges I could rest my tired corpse on the way up this climb. I used them a lot in the blazing heat that night.
The ride in the valley from Amulree to the foot of the climb was also highly enjoyable. Not to mention; very beautiful. In short; Glen Quaich Road and/or the road from Crieff over the Sma Glen and Glen Quaich Road to Kenmore should be on every bikeriders to-do list. I loved it and will do it again as the two days tour I did Tuesday-Wedensday. A special mention to the beauty of the Sma Glen too. It is only 2 miles long, but it packs a punch like no other valley does in Scotland. I say no more....