I can't answer your specific questions, but I do own a Marvel Unit One. They are expensive and you can find cheaper .22 conversions, but I don't think you can find any of higher quality. They are also tack drivers. I think the Unit one has a guaranteed accuracy of 1" at 50 yards. Mine came with a test target showing a group of under 1/2" at that distance. Out of a 5 inch pistol barrel that's pretty amazing accuracy.
Also, installing the unit on an existing 1911 frame is a snap.
Marvels aren't cheap (although you can actually save money if you don't buy it directly from Marvel). However, if you want a high quality, extremely accurate .22 conversion unit they are tough to beat. If price is an issue, just shoot it a lot and think of how much money you've saved by using .22 ammo.
The answer to your question is yes the Marvel barrel has a build-in feed ramp.
I have had my Unit 1 installed on frames with and without the ramp barrel cut and it work great on either. Like pippin stated they are not the cheapest but I think it is money well spent. I shoot mine almost everyday what fun.
On another note I got one of the Ciener 15 round magazines and it works great with my Marvel unit 1. A 15 round 22/1911
Most 22 conversion units have their own ramp...Specifically the Unit 1 does and fits on all the frames I have tried it on..Mine is now on an STI frame that used to be an IPSC open gun that has a frame cut.
I also removed the ejector..since this is the units home. and that is not needed.
I think the Marvel is worth the price..especially if you shoot the different 22lr competitions..
C-rum..where did you find your 15rnd Ceiner mag?? that sounds pretty cool
I was thinking about sending my five 10 round Ciener magazines for my 1911 unit in to be converted to fifteen round capacity. I see it would cost $80 to get them done. I think the ten rounders will do.