You can get way behind in a 737 and get in trouble in almost all aspects (i.e. flying, or FMS, or systems, etc.) a lot easier and quicker than any Regional aircraft. Anybody who tells you different or that it is basically "the same" is being either disingenuous or woefully out of touch. Yoou know the type, they've been in the 737 way too long to know different, basically any Legacy guy who has been there more than 10 years which is why they always give such horrible advice to new pilots.