I would be happy to take the train and ride my bike. I think a train coming along 2 or 3 times a day would make it more interesting. I don't understand why the trail people are so opposed to the train. The train people aren't opposed to having a trail too. I don't see how putting the trail next to the track would cost any more than tearing out the track and putting it on top of it. Why is only having a trail better than having both? If the rail people want to do the work let them and I'd be glad to make a donation.
Yes, the combination of the train and a bike path would be ideal; in fact, they are quite complimentary, as the train can double the range of cyclists (take the train up the hill and ride back down). My wife and I once combined the Durango-Silverton RR and biking into an awesome three-day, 100-mile tour. The issue is that this is not an ideal situation. In general, it is significantly cheaper to build a bike path on the rail bed than alongside it because most of the grading is already done, the drainage requires only minor modifications and, most importantly, the bridges and culverts can be re-used without building new ones. However, because of the rugged terrain and variable ROW width along the corridor through El Dorado County, the cost of building alongside the tracks is even greater, and there are some sections where it is just not feasible to do so. So, it is easy for the rail folks to simply say that they are fine with having both, but all the added cost of having both goes to the construction of the path, delaying it by years at best, and at worst resulting in significant gaps in the corridor.
On the rail side, the question that has to be answered is: is a 30-mile excursion train really a feasible possibility? Rail groups in Folsom and El Dorado County have been working hard for over twenty years (and I do would never doubt the dedication or perseverance of rail buffs), but neither yet has a regularly-scheduled excursion train of even a mile or two. So the question is, is it a reasonable use of a publicly-owned transportation corridor to preserve large swaths of corridor for excursion rail that is unlikely to ever happen. To be clear, I'm not saying that I don't think excursion rail will happen. What I'm saying is that a 30-mile excursion train is highly unlikely. I do not doubt, and would welcome, excursion trains from Folsom and/or El Dorado. But the proposal for removing tracks is for the middle third or so from Latrobe to Shingle Springs. This includes most of the stretches that would be most difficult to build a path alongside the tracks, and the stretches least likely to have trains running on them. I would also note that from Missouri Flat Rd east, the tracks have long been removed and a very popular bike path has been constructed (partly on the old Michican-CA Lumber RR grade east of Placerville) almost all the way to Camino (with a significant gap in western Placerville).
In a best-case scenario, an excursion train running on weekends may carry a couple thousand passengers a week. A bike path on the same corridor would be used by 10s of thousands of bicyclists, walkers, joggers, mom's with strollers, people in wheelchairs, etc. every week, seven days a week, up to 16 hours a day, just as the ARP now is. This isn't primarily about Folsom, this is about providing transportation and recreation options in western El Dorado County, where currently most parents would not let their 5-year-old ride past the end of their driveway.
Oh, and speaking of 5-year-olds, we're on our fourth one right now, and the first three were all quite capable of riding a single speed bike the 5 miles of 5% to 7% grades from Folsom to Beale's point (the fourth one is just short of that right now) and quite happily would ride the 12 miles around Lake Natoma, complete with its series of rolling hills. A 2-3% RR grade really is child's play on a bicycle (sidewalks are sloped 2% across so they drain; the ADA considers anything less than 2% as level for a wheelchair). Anybody who thinks a 5-year-old cannot ride 5 miles on a bike trail hasn't taken a 5-year-old on a bike trail more than once a month.